ORCID Profile
0000-0002-9962-8919
Current Organisations
University of Technology, Sydney (UTS)
,
University of Technology Sydney
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Turbulent Flows | Navigation and Position Fixing | Interdisciplinary Engineering | Biomechanical Engineering | Mechanical Engineering | Numerical Modelling and Mechanical Characterisation | Environmental Engineering Modelling
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in Engineering | Health and Support Services not elsewhere classified | Environmental and Natural Resource Evaluation not elsewhere classified | Coastal and Estuarine Water Management |
Related Links
Publications
Natural convection due to differential heating of inclined walls and heat source placed on bottom wall of an attic shaped space
Publisher: Elsevier BV
Date: 02-2015
Euler–Lagrange approach to investigate respiratory anatomical shape effects on aerosol particle transport and deposition
Publisher: SAGE Publications
Date: 2019
Abstract: An accurate knowledge of the pulmonary aerosol particle transport in the realistic lung is essential to deliver the therapeutic particle to the targeted site of the bifurcating airways. The available in silico studies have enriched the knowledge of the aerosol transport and deposition (TD) in the lung however, the absolute TD data in the realistic lung airway are still elusive. Therefore, in this study, a 3-D geometry of the human lung central airway is developed from the computed tomography (CT) images. A CT scan-based modified lung geometry with a smooth surface and nonrealistic Weibel’s lung geometry is also generated. The coal mine exhausted aerosol TD in the upper airway is investigated. The Euler–Lagrange (E-L) method for particle tracking and ANSYS Fluent solver are used to carry out the entire investigation. The effective diameter method is employed to define the shape-specific particles and is integrated with the E-L method. The anatomical shape effects on the deposition patterns are investigated for different deposition parameter. The numerical results illustrated that the airway geometry, particle shape, particle diameter, and breathing flow rates significantly influence the aerosol TD pattern in the upper airway. The present study reports that airway tracheal wall is the new deposition hot spot for the CT-based geometry instead of bifurcating area for the idealized model, which might be helpful for zone-specific drug delivery to the respiratory airways.
Viscous Dissipation Effects on Natural Convection from a Vertical Plate with Uniform Surface Heat Flux Placed in a Thermally Stratified Media
Publisher: Begell House
Date: 2005
Airflow and Particle Transport to the Terminal Bronchioles During Heliox Breathing
Publisher: Springer Singapore
Date: 2021
Is the SARS CoV-2 Omicron Variant Deadlier and More Transmissible Than Delta Variant?
Publisher: MDPI AG
Date: 11-04-2022
Abstract: Genetic variants of severe acute respiratory syndrome coronavirus (SARS-CoV-2) have been globally surging and devastating many countries around the world. There are at least eleven reported variants dedicated with inevitably catastrophic consequences. In 2021, the most dominant Delta and Omicron variants were estimated to lead to more severity and deaths than other variants. Furthermore, these variants have some contagious characteristics involving high transmissibility, more severe illness, and an increased mortality rate. All outbreaks caused by the Delta variant have been rapidly skyrocketing in infection cases in communities despite tough restrictions in 2021. Apart from it, the United States, the United Kingdom and other high-rate vaccination rollout countries are still wrestling with this trend because the Delta variant can result in a significant number of breakthrough infections. However, the pandemic has changed since the latest SARS-CoV-2 variant in late 2021 in South Africa, Omicron. The preliminary data suggest that the Omicron variant possesses 100-fold greater than the Delta variant in transmissibility. Therefore, this paper aims to review these characteristics based on the available meta-data and information from the first emergence to recent days. Australia and the five most affected countries, including the United States, India, Brazil, France, as well as the United Kingdom, are selected in order to review the transmissibility, severity and fatality due to Delta and Omicron variants. Finally, the vaccination programs for each country are also reviewed as the main factor in prevention.
Prandtl number scaling of the unsteady natural convection boundary layer adjacent to a vertical flat plate for Pr > 1 subject to ramp surface heat flux
Publisher: Elsevier BV
Date: 11-2012
Numerical investigation of diesel exhaust particle transport and deposition in the CT-scan based lung airway
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4984721
Deformation behaviour of stomatocyte, discocyte and echinocyte red blood cell morphologies during optical tweezers stretching
Publisher: Springer Science and Business Media LLC
Date: 25-02-2020
Deformation of a single red blood cell in a microvessel
Publisher: Australian Mathematical Publishing Association, Inc.
Date: 23-04-2014
Investigation of correlation between chemical composition and properties of biodiesel using principal component analysis (PCA) and artificial neural network (ANN)
Publisher: Elsevier BV
Date: 05-2021
Effect of Fluctuating Surface Heat and Mass Flux on Natural Convection Flow along a Vertical Flat Plate
Publisher: Hindawi Limited
Date: 2015
DOI: 10.1155/2015/258016
Abstract: An investigation has been carried on double diffusive effect on boundary layer flow due to small litude oscillation in surface heat and mass flux. Extensive parametric simulations were performed in order to elucidate the effects of some important parameters, that is, Prandtl number, Schmidt number, and Buoyancy ratio parameter on flow field in conjunction with heat and mass transfer. Asymptotic solutions for low and high frequencies are obtained for the conveniently transformed governing coupled equations. Solutions are also obtained for wide ranged value of the frequency parameters. Comparisons between the asymptotic and wide ranged values are made in terms of the litudes and phases of the shear stress, surface heat transfer, and surface mass transfer. It has been found that the litudes and phase angles obtained from asymptotic solutions are found in good agreement with the finite difference solutions obtained for wide ranged value of the frequency parameter.
Effect of Reynolds numbers on flow past four square cylinders in an in-line square configuration for different gap spacings
Publisher: Springer Science and Business Media LLC
Date: 02-2014
Transient natural convection in a valley shaped triangular cavity initially filled with stratified water
Publisher: Author(s)
Date: 2016
DOI: 10.1063/1.4958420
2D study of the bifurcations in a V-shaped cavity
Publisher: AIP Publishing
Date: 2021
DOI: 10.1063/5.0037667
Heat transfer enhancement investigation in a novel flat plate heat exchanger
Publisher: Elsevier BV
Date: 03-2021
Numerical study of nano and micro pollutant particle transport and deposition in realistic human lung airways
Publisher: Elsevier BV
Date: 04-2022
Parametric Analysis of Design Parameter Effects on the Performance of a Solar Desiccant Evaporative Cooling System in Brisbane, Australia
Publisher: MDPI AG
Date: 25-06-2017
DOI: 10.3390/EN10070849
Hydrogen production via electrolysis: Mathematical modeling approach
Publisher: Elsevier
Date: 2021
Radiation effect on free convection laminar flow along a vertical flat plate with streamwise sinusoidal surface temperature
Publisher: Elsevier BV
Date: 03-2011
A three-dimensional simulation of transient natural convection in a triangular cavity
Publisher: Elsevier BV
Date: 06-2015
Formation of the three-dimensional geometry of the red blood cell membrane
Publisher: Australian Mathematical Publishing Association, Inc.
Date: 07-05-2014
Transient air flow and heat transfer in a triangular enclosure with a conducting partition
Publisher: Elsevier BV
Date: 08-2014
Magnetic convection heat transfer in an open ended enclosure filled with paramagnetic fluids
Publisher: Trans Tech Publications, Ltd.
Date: 05-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.109
Abstract: Numerical simulations of thermomagnetic convection of paramagnetic fluids placed in a micro-gravity condition (g ≈ 0) and under a uniform vertical gradient magnetic field in an open ended square enclosure with r heating temperature condition applied on a vertical wall is investigated in this study. In presence of the strong magnetic gradient field thermal convection of the paramagnetic fluid might take place even in a zero-gravity environment as a direct consequence of temperature differences occurring within the fluid. The thermal boundary layer develops adjacent to the hot wall as soon as the r temperature condition is applied on it. There are two scenario that can be observed based on the r heating time. The steady state of the thermal boundary layer can be reached before the r time is finished or vice versa. If the r time is larger than the quasi-steady time then the thermal boundary layer is in a quasi-steady mode with convection balancing conduction after the quasi-steady time. Further increase of the heat input simply accelerates the flow to maintain the proper thermal balance. Finally, the boundary layer becomes completely steady state when the r time is finished. Effects of magnetic Rayleigh number, Prandtl number and paramagnetic fluid parameter on the flow pattern and heat transfer are presented.
Comparison of wake structures and force measurements behind three side-by-side cylinders
Publisher: Springer Science and Business Media LLC
Date: 16-12-2014
Prandtl number scaling of natural convection of an inclined flat plate due to uniform surface heat flux
Publisher: Australian Mathematical Publishing Association, Inc.
Date: 16-07-2012
Free convection in a triangular enclosure with fluid-saturated porous medium and internal heat generation
Publisher: Australian Mathematical Publishing Association, Inc.
Date: 20-05-2012
Surface tension effects on flow dynamics and alveolar mechanics in the acinar region of human lung
Publisher: Elsevier BV
Date: 10-2022
Natural convection in a triangular enclosure due to non-uniform cooling on top
Publisher: Australian Mathematical Publishing Association, Inc.
Date: 26-04-2012
Heat transfer and fluid flow analysis in a realistic 16-generation lung
Publisher: AIP Publishing
Date: 06-2022
DOI: 10.1063/5.0093912
Abstract: Heat transfer between inhaled hot/cool air and the lung surface within the human respiratory system is an intriguing topic that has not received enough attention. The lung can be considered an in vivo heat exchanger, balancing the inhaled air temperature by lowering the hot air temperature and increasing the cool air temperature. The current work studies the unsteady and incompressible airflow motion and heat transfer during inhalation between the surface of the lungs (37 °C) and the inhaled cool air (25 °C) in one case and inhaled hot air (43 °C) in another. Computerized tomography scan (CT-scan) images of the lung of a 39-year-old male patient were processed to generate the airway geometry consisting of 16 generations. The geometry was further modified in UG NX 12.0, and the mesh generation was carried out using Ansys Meshing. The shear stress transport (SST) k−ω turbulent model was employed in Ansys Fluent 20.2 to model the air/lung convective volume heat transfer utilizing a realistic breathing velocity profile. Temperature streamlines, lung volume temperatures, surface heat flux, and surface temperatures on all 16 generations were produced for both cases during the breathing cycle of 4.75 s. Several conclusions were made by studying and comparing the two cases. First, heat transfer between inhaled hot or cool air and the lung surface mainly occurred in the first few generations. Second, airflow temperature patterns are dependent on the inlet breathing velocity profile. Third, the lung volume temperature change directly correlates with the temperature difference between air and the lung surface. Finally, the surface heat flux strongly depended on the heat transfer coefficient. The density, viscosity, thermal conductivity, and specific heat of hot/cool air affected the Reynolds number, Nusselt number, heat transfer coefficient, and surface heat flux.
Conjugate forced convection transient flow and heat transfer analysis in a hexagonal, partitioned, air filled cavity with dynamic modulator
Publisher: Elsevier BV
Date: 03-2021
Aerosol particle transport and deposition in a CT-scan based mouth-throat model
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5115882
Unsteady Natural Convection in an Initially Stratified Air-Filled Trapezoidal Enclosure Heated from Below
Publisher: MDPI AG
Date: 15-07-2022
DOI: 10.3390/PR10071383
Abstract: Natural convection is intensively explored, especially in a valley-shaped trapezoidal enclosure, because of its broad presence in both technical settings and nature. This study deals with a trapezoidal cavity, which is initially filled with linearly stratified air. Although the sidewalls remain adiabatic, the bottom wall is heated, and the top wall is cooled. For the stratified fluid (air), the temperature of the fluid adjacent to the top and the bottom walls is the same as that of the walls. Natural convection in the trapezoidal cavity is simulated in two dimensions using numerical simulations, by varying Rayleigh numbers (Ra) from 100 to 108 with constant Prandtl number, Pr = 0.71, and aspect ratio, A = 0.5. The numerical results demonstrate that the development of natural convection from the beginning is dependent on the Rayleigh numbers. According to numerical results, the development of transient flow within the enclosure owing to the predefined conditions for the boundary may be categorized into three distinct stages: early, transitional, and steady or unsteady. The flow characteristics at each of the three phases and the impact of the Rayleigh number on the flow’s growth are quantified. Unsteady natural convection flows in the enclosure are described and validated by numerical results. In addition, heat transfer through the bottom and the top surfaces is described in this study.
Euler-Lagrange Prediction of Diesel-Exhaust Polydisperse Particle Transport and Deposition in Lung: Anatomy and Turbulence Effects
Publisher: Springer Science and Business Media LLC
Date: 27-08-2019
DOI: 10.1038/S41598-019-48753-6
Abstract: In clinical assessments, the correlation between atmospheric air pollution and respiratory damage is highly complicated. Epidemiological studies show that atmospheric air pollution is largely responsible for the global proliferation of pulmonary disease. This is particularly significant, since most Computational Fluid Dynamics (CFD) studies to date have used monodisperse particles, which may not accurately reflect realistic inhalation patterns, since atmospheric aerosols are mostly polydisperse. The aim of this study is to investigate the anatomy and turbulent effects on polydisperse particle transport and deposition (TD) in the upper airways. The Euler-Lagrange approach is used for polydisperse particle TD prediction in both laminar and turbulent conditions. Various anatomical models are adopted to investigate the polydisperse particle TD under different flow conditions. Rossin-Rammler diameter distribution is used for the distribution of the initial particle diameter. The numerical results illustrate that airflow rate distribution at the right lung of a realistic model is higher than a non-realistic model. The CFD study also shows that turbulence effects on deposition are higher for larger diameter particles than with particles of smaller diameter. A significant amount of polydisperse particles are also shown to be deposited at the tracheal wall for CT-based model, whereas particles are mostly deposited at the carinal angle for the non-realistic model. A comprehensive, polydisperse particle TD analysis would enhance understanding of the realistic deposition pattern and decrease unwanted therapeutic aerosol deposition at the extrathoracic airways.
Conduction-radiation effect on natural convection flow in fluid-saturated non-Darcy porous medium enclosed by non-isothermal walls
Publisher: Springer Science and Business Media LLC
Date: 18-05-2013
Enhancement of Confined Air Jet Impingement Heat Transfer Using Perforated Pin-Fin Heat Sinks
Publisher: Springer Singapore
Date: 04-10-2017
Mixed Convection Flow of Micropolar Fluid in an Open Ended Arc-Shape Cavity
Publisher: ASME International
Date: 21-08-2012
DOI: 10.1115/1.4007268
Abstract: Numerical simulations for mixed convection flow of micropolar fluid in an open ended arc-shape cavity have been carried out in this study. Computation is performed using the alternate direct implicit (ADI) method together with the successive over relaxation (SOR) technique for the solution of governing partial differential equations. The flow phenomenon is examined for a range of values of Rayleigh number 102 ≤ Ra ≤ 106, Prandtl number 7 ≤ Pr ≤ 50, and Reynolds number 10 ≤ Re ≤ 100. The study is mainly focused on how the micropolar fluid parameters affect the fluid properties in the flow domain. It was found that despite the reduction of flow in the core region, the heat transfer rate increases, whereas the skin friction and microrotation decrease with the increase in the vortex viscosity parameter Δ.
Unsteady natural convection in a triangular enclosure under isothermal heating
Publisher: Elsevier BV
Date: 02-2011
Unsteady buoyancy driven flows and heat transfer through coupled thermal boundary layers in a partitioned triangular enclosure
Publisher: Elsevier BV
Date: 2014
Natural Convection Flow in a Strong Cross Magnetic Field With Radiation
Publisher: ASME International
Date: 08-04-2013
DOI: 10.1115/1.4023854
Abstract: The problem of magnetohydrodynamic natural convection boundary layer flow of an electrically conducting and optically dense gray viscous fluid along a heated vertical plate is analyzed in the presence of strong cross magnetic field with radiative heat transfer. In the analysis radiative heat flux is considered by adopting optically thick radiation limit. Attempt is made to obtain the solutions valid for liquid metals by taking Pr ≪1. Boundary layer equations are transformed in to a convenient dimensionless form by using stream function formulation (SFF) and primitive variable formulation (PVF). Nonsimilar equations obtained from SFF are then simulated by implicit finite difference (Keller-box) method whereas parabolic partial differential equations obtained from PVF are integrated numerically by hiring direct finite difference method over the entire range of local Hartmann parameter, ξ. Further, asymptotic solutions are also obtained for large and small values of local Hartmann parameter ξ. A favorable agreement is found between the results for small, large and all values of ξ. Numerical results are also demonstrated graphically by showing the effect of various physical parameters on shear stress, rate of heat transfer, velocity, and temperature.
Structural and functional alterations of the tracheobronchial tree after left upper pulmonary lobectomy for lung cancer
Publisher: Springer Science and Business Media LLC
Date: 25-10-2019
DOI: 10.1186/S12938-019-0722-6
Abstract: Pulmonary lobectomy has been a well-established curative treatment method for localized lung cancer. After left upper pulmonary lobectomy, the upward displacement of remaining lower lobe causes the distortion or kink of bronchus, which is associated with intractable cough and breathless. However, the quantitative study on structural and functional alterations of the tracheobronchial tree after lobectomy has not been reported. We sought to investigate these alterations using CT imaging analysis and computational fluid dynamics (CFD) method. Both preoperative and postoperative CT images of 18 patients who underwent left upper pulmonary lobectomy are collected. After the tracheobronchial tree models are extracted, the angles between trachea and bronchi, the surface area and volume of the tree, and the cross-sectional area of left lower lobar bronchus are investigated. CFD method is further used to describe the airflow characteristics by the wall pressure, airflow velocity, lobar flow rate, etc. It is found that the angle between the trachea and the right main bronchus increases after operation, but the angle with the left main bronchus decreases. No significant alteration is observed for the surface area or volume of the tree between pre-operation and post-operation. After left upper pulmonary lobectomy, the cross-sectional area of left lower lobar bronchus is reduced for most of the patients (15/18) by 15–75%, especially for 4 patients by more than 50%. The wall pressure, airflow velocity and pressure drop significantly increase after the operation. The flow rate to the right lung increases significantly by 2–30% (but there is no significant difference between each lobe), and the flow rate to the left lung drops accordingly. Many vortices are found in various places with severe distortions. The favorable and unfavorable adaptive alterations of tracheobronchial tree will occur after left upper pulmonary lobectomy, and these alterations can be clarified through CT imaging and CFD analysis. The severe distortions at left lower lobar bronchus might exacerbate postoperative shortness of breath.
Effect of aspect ratio on natural convection in attics subject to periodic thermal forcing
Publisher: Australian Mathematical Publishing Association, Inc.
Date: 20-12-2007
Entropy Production Analysis in an Octagonal Cavity with an Inner Cold Cylinder: A Thermodynamic Aspect
Publisher: MDPI AG
Date: 19-07-2023
DOI: 10.3390/EN16145487
Abstract: Understanding fluid dynamics and heat transfer is crucial for designing and improving various engineering systems. This study examines the heat transfer characteristics of a buoyancy-driven natural convection flow that is laminar and incompressible. The investigation also considers entropy generation (Egen) within an octagonal cavity subject to a cold cylinder inside the cavity. The dimensionless version of the governing equations and their corresponding boundary conditions have been solved numerically using the finite element method, employing triangular mesh elements for discretization. The findings indicated that incorporating a cold cylinder inside the octagonal cavity resulted in a higher heat transfer (HT) rate than in the absence of a cold cylinder. Furthermore, using the heat flux condition led to a higher average Nusselt number (Nuavg) and a lower Bejan number (Be) than the isothermal boundary condition. The results also showed that HT and Egen were more significant in the Al2O3-H2O nanofluid than the basic fluids such as air and water, and HT increased as χ increased. The current research demonstrates that employing the heat flux condition and incorporating nanoparticles can enhance the rate of HT and Egen. Furthermore, the thermo-fluid system should be operated at low Ra to achieve greater HT effectiveness for nanofluid concerns.
Computational Studies of Lipid-Wrapped Gold Nanoparticle Transport Through Model Lung Surfactant Monolayers
Publisher: American Chemical Society (ACS)
Date: 02-02-2021
Investigation of red blood cell mechanical properties using AFM indentation and coarse-grained particle method
Publisher: Springer Science and Business Media LLC
Date: 12-2017
Thermal performance investigation in a novel corrugated plate heat exchanger
Publisher: Elsevier BV
Date: 02-2020
MHD Mixed Convection of Non-Newtonian Bingham Nanofluid in a Wavy Enclosure with Temperature-Dependent Thermophysical Properties: A Sensitivity Analysis by Response Surface Methodology
Publisher: MDPI AG
Date: 30-05-2023
DOI: 10.3390/EN16114408
Abstract: The numerical investigation of magneto-hydrodynamic (MHD) mixed convection flow and entropy formation of non-Newtonian Bingham fluid in a lid-driven wavy square cavity filled with nanofluid was investigated by the finite volume method (FVM). The numerical data-based temperature and nanoparticle size-dependent correlations for the Al2O3-water nanofluids are used here. The physical model is a two-dimensional wavy square cavity with thermally adiabatic horizontal boundaries, while the right and left vertical walls maintain a temperature of TC and TH, respectively. The top wall has a steady speed of u=u0. Pertinent non-dimensional parameters such as Reynolds number (Re=10,100,200,400), Hartmann number (Ha=0,10,20), Bingham number (Bn=0,2,5,10,50,100,200), nanoparticle volume fraction (ϕ=0,0.02,0.04), and Prandtl number (Pr=6.2) have been simulated numerically. The Richardson number Ri is calculated by combining the values of Re with a fixed value of Gr, which is the governing factor for the mixed convective flow. Using the Response Surface Methodology (RSM) method, the correlation equations are obtained using the input parameters for the average Nusselt number (Nu¯), total entropy generation (Es)t, and Bejan number (Beavg). The interactive effects of the pertinent parameters on the heat transfer rate are presented by plotting the response surfaces and the contours obtained from the RSM. The sensitivity of the output response to the input parameters is also tested. According to the findings, the mean Nusselt numbers (Nu¯) drop when Ha and Bn are increased and grow when Re and ϕ are augmented. It is found that (Es)t is reduced by raising Ha, but (Es)t rises with the augmentation of ϕ and Re. It is also found that the ϕ and Re numbers have a positive sensitivity to the Nu¯, while the sensitivity of the Ha and Bn numbers is negative.
Double Diffusive Magneto-Convection Fluid Flow in a Strong Cross Magnetic Field With Uniform Surface Heat and Mass Flux
Publisher: ASME International
Date: 28-09-2012
DOI: 10.1115/1.4007130
Abstract: In this study, magnetohydrodynamic natural convection boundary layer flow of an electrically conducting and viscous incompressible fluid along a heated vertical flat plate with uniform heat and mass flux in the presence of strong cross magnetic field has been investigated. Asymptotic solutions are obtained for small (≪1) and large (≫1) values of local Hartmann parameter, ξ, through regular perturbation method and matched asymptotic expansion technique, respectively. However, for all values of ξ the boundary layer equations are transformed to a suitable form by using the free variable formulation (FVF) as well as the stream function formulation (SFF). The equations obtained through FVF are integrated via direct finite difference method together with Gaussian elimination technique while the others obtained through SFF are integrated numerically via Thomas algorithm. Discussion is carried out for fluids having small Pr ≪1. The results obtained for small, large and all ξ regimes are examined in terms of shear stress, τw, rate of heat transfer, qw, and rate of mass transfer, mw, for important physical parameter. Attention has been given to the influence of Schmidt number, Sc, buoyancy ratio parameter, N and local Hartmann parameter, ξ on velocity, temperature and concentration distributions and noted that velocity and temperature of the fluid achieve their asymptotic profiles for Sc ≥ 10.0.
Comparison of flow resistance and port maldistribution between novel and conventional plate heat exchangers
Publisher: Elsevier BV
Date: 04-2021
Non-newtonian Mixed Convection Flow from a Horizontal Circular Cylinder with Uniform Surface Heat Flux
Publisher: Elsevier BV
Date: 2014
Numerical investigation of flow past a row of rectangular rods
Publisher: Elsevier BV
Date: 09-2016
Equality in education: Fairness and inclusion
Publisher: SensePublishers
Date: 2014
Helium–oxygen mixture model for particle transport in CT-based upper airways
Publisher: MDPI AG
Date: 20-05-2020
Abstract: The knowledge of respiratory particle transport in the extra-thoracic pathways is essential for the estimation of lung health-risk and optimization of targeted drug delivery. The published literature reports that a significant fraction of the inhaled aerosol particles are deposited in the upper airways, and available inhalers can deliver only a small amount of drug particles to the deeper airways. To improve the targeted drug delivery efficiency to the lungs, it is important to reduce the drug particle deposition in the upper airways. This study aims to minimize the unwanted aerosol particle deposition in the upper airways by employing a gas mixture model for the aerosol particle transport within the upper airways. A helium–oxygen (heliox) mixture (80% helium and 20% oxygen) model is developed for the airflow and particle transport as the heliox mixture is less dense than air. The mouth–throat and upper airway geometry are extracted from CT-scan images. Finite volume based ANSYS Fluent (19.2) solver is used to simulate the airflow and particle transport in the upper airways. Tecplot software and MATLAB code are employed for the airflow and particle post-processing. The simulation results show that turbulence intensity for heliox breathing is lower than in the case of air-breathing. The less turbulent heliox breathing eventually reduces the deposition efficiency (DE) at the upper airways than the air-breathing. The present study, along with additional patient-specific investigation, could improve the understanding of particle transport in upper airways, which may also increase the efficiency of aerosol drug delivery.
Natural convection flow in porous enclosure with localized heating from below with heat flux
Publisher: Author(s)
Date: 2016
DOI: 10.1063/1.4958407
Decarbonizing the Atmosphere Using Carbon Capture, Utilization, and Sequestration: Challenges, Opportunities, and Policy Implications in India
Publisher: MDPI AG
Date: 10-10-2023
Aerosol particle transport and deposition in upper and lower airways of infant, child and adult human lungs
Publisher: MDPI AG
Date: 26-10-2021
Abstract: Understanding transportation and deposition (TD) of aerosol particles in the human respiratory system can help clinical treatment of lung diseases using medicines. The lung airway diameters and the breathing capacity of human lungs normally increase with age until the age of 30. Many studies have analyzed the particle TD in the human lung airways. However, the knowledge of the nanoparticle TD in airways of infants and children with varying inhalation flow rates is still limited in the literature. This study investigates nanoparticle (5 nm ≤ dp ≤ 500 nm) TD in the lungs of infants, children, and adults. The inhalation air flow rates corresponding to three ages are considered as Qin=3.22 L/min (infant), 8.09 L/min (Child), and Qin=14 L/min (adult). It is found that less particles are deposited in upper lung airways (G0–G3) than in lower airways (G12–G15) in the lungs of all the three age groups. The results suggest that the particle deposition efficiency in lung airways increases with the decrease of particle size due to the Brownian diffusion mechanism. About 3% of 500 nm particles are deposited in airways G12–G15 for the three age groups. As the particle size is decreased to 5 nm, the deposition rate in G12–G15 is increased to over 95%. The present findings can help medical therapy by in idually simulating the distribution of drug-aerosol for the patient-specific lung.
Conjugate natural convection in a vertically divided square enclosure by a corrugated solid partition into air and water regions
Publisher: Elsevier BV
Date: 10-2021
Control of flow around a circular cylinder wrapped with a porous layer by magnetohydrodynamic
Publisher: Elsevier BV
Date: 03-2016
Flows and heat transfer of the transition to an unsteady state in a finned cavity for different Prandtl numbers
Publisher: Elsevier BV
Date: 11-2017
Natural convection subject to sinusoidal thermal forcing on inclined walls and heat source located on bottom wall of an attic-shaped space
Publisher: Elsevier BV
Date: 09-2016
Scaling analysis of intrusion flow and thermal plume for Pr > 1 in the triangular cavity
Publisher: Elsevier BV
Date: 2024
Exposure Assessment of Air Pollution in Lungs
Publisher: MDPI AG
Date: 27-10-2022
Chaotic phenomena of natural convection for water in a V-shaped enclosure
Publisher: Elsevier BV
Date: 06-2022
Natural convection heat transfer in the partitioned attic space
Publisher: Elsevier
Date: 2016
Molecular dynamics study of prednisolone concentration on cholesterol based lung surfactant monolayer
Publisher: AIP Publishing
Date: 2021
DOI: 10.1063/5.0037471
Two-phase natural convection flow of a dusty fluid
Publisher: Emerald
Date: 07-09-2015
Abstract: – The purpose of this paper is to conduct a detailed investigation of the two-dimensional natural convection flow of a dusty fluid. Therefore, the incompressible boundary layer flow of a two-phase particulate suspension is investigated numerically over a semi-infinite vertical flat plate. Comprehensive flow formations of the gas and particle phases are given in the boundary layer region. Primitive variable formulation is employed to convert the nondimensional governing equations into the non-conserved form. Three important two-phase mechanisms are discussed, namely, water-metal mixture, oil-metal mixture and air-metal mixture. – The full coupled nonlinear system of equations is solved using implicit two point finite difference method along the whole length of the plate. – The authors have presented numerical solution of the dusty boundary layer problem. Solutions obtained are depicted through the characteristic quantities, such as, wall shear stress coefficient, wall heat transfer coefficient, velocity distribution and temperature distribution for both phases. Results are interpreted for wide range of Prandtl number Pr (0.005-1,000.0). It is observed that thin boundary layer structures can be formed when mass concentration parameter or Prandtl number (e.g. oil-metal particle mixture) are high. – The results of the study may be of some interest to the researchers of the field of chemical engineers.
Modeling of thermal performance of a commercial alkaline electrolyzer supplied with various electrical currents
Publisher: Elsevier BV
Date: 02-2022
Numerical Study of Natural Convection Flow in Rectangular Cavity with Viscous Dissipation and Internal Heat Generation for Different Aspect Ratios
Publisher: MDPI AG
Date: 10-07-2023
DOI: 10.3390/EN16145267
Abstract: Numerical simulations have been performed to investigate the influence of constant volumetric heat generation and viscous dissipation on the unsteady natural convection flow of an incompressible Newtonian fluid contained in a rectangular cavity. The left vertical wall of the cavity is cooled, while the right vertical wall is heated, and the bottom and top walls are adiabatic. A numerical technique based on the implicit finite difference method (IFDM), along with an upwind finite difference scheme and an iterative successive over relaxation (SOR) technique, is employed to solve the governing equations numerically. The effect of physical parameters, namely the modified Rayleigh number (103≤Ra≤107), aspect ratio (1≤A≤4), Prandtl number (Pr=0.7, 1.0, 6.2, 15), volumetric internal heat generation parameter (Qλ=0, 1), and Eckert number (0≤Ec≤10−6), on the streamlines and isotherms are discussed graphically. Variations of maximum stream function, as well as average and local Nusselt number, are also discussed. The results show that the increase in Eckert number from 0 to 10−4 causes the average heat transfer to decrease, while Pr=0.71, Ra=104, and Qλ=0. Additionally, the average heat transfer decreases as the cavity width increases from 1 to 4, while Pr=0.71, Ra = 5×104, Ec=10−6 and Qλ=1. The results of the numerical model used here are in excellent accord with earlier findings.
A multiscale modeling method incorporating spatial coupling and temporal coupling into transient simulations of the human airways
Publisher: Wiley
Date: 09-06-2021
DOI: 10.1002/FLD.5015
Abstract: In this article, a novel multiscale modeling method is proposed for transient computational fluid dynamics (CFD) simulations of the human airways. The developed method is the first attempt to incorporate spatial coupling and temporal coupling into transient human airway simulations, aiming to improve the flexibility and the efficiency of these simulations. In this method, domain decomposition was used to separate the complex airway model into different scaled domains. Each scaled domain could adopt a suitable mesh and timestep, as necessary: the coarse mesh and large timestep were employed in the macro regions to reduce the computational cost, while the fine mesh and small timestep were used in micro regions to maintain the simulation accuracy. The radial point interpolation method was used to couple data between the coarse mesh and the fine mesh. The continuous micro solution–intermittent temporal coupling method was applied to bridge different timesteps. The developed method was benchmarked using a well‐studied four‐generation symmetric airway model under realistic normal breath conditions. The accuracy and efficiency of the method were verified separately in the inhalation phase and the exhalation phase. Similar airflow behavior to previous studies was observed from the multiscale airway model. The developed multiscale method has the potential to improve the flexibility and efficiency of transient human airway simulations without sacrificing accuracy.
Asymmetric natural convection flow in three dimensional attic space
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5114485
Realistic Human Airway Simulations by a Novel Multiscale Method
Publisher: Elsevier BV
Date: 2022
DOI: 10.2139/SSRN.4107064
Retrieval, reporting and methodological characteristics for systematic reviews/meta-analyses of animal models: a metaepidemiological study
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 2020
A Review of Respiratory Anatomical Development, Air Flow Characterization and Particle Deposition
Publisher: MDPI AG
Date: 07-01-2020
Abstract: The understanding of complex inhalation and transport processes of pollutant particles through the human respiratory system is important for investigations into dosimetry and respiratory health effects in various settings, such as environmental or occupational health. The studies over the last few decades for micro- and nanoparticle transport and deposition have advanced the understanding of drug-aerosol impacts in the mouth-throat and the upper airways. However, most of the Lagrangian and Eulerian studies have utilized the non-realistic symmetric anatomical model for airflow and particle deposition predictions. Recent improvements to visualization techniques using high-resolution computed tomography (CT) data and the resultant development of three dimensional (3-D) anatomical models support the realistic representation of lung geometry. Yet, the selection of different modelling approaches to analyze the transitional flow behavior and the use of different inlet and outlet conditions provide a dissimilar prediction of particle deposition in the human lung. Moreover, incorporation of relevant physical and appropriate boundary conditions are important factors to consider for the more accurate prediction of transitional flow and particle transport in human lung. This review critically appraises currently available literature on airflow and particle transport mechanism in the lungs, as well as numerical simulations with the aim to explore processes involved. Numerical studies found that both the Euler–Lagrange (E-L) and Euler–Euler methods do not influence nanoparticle (particle diameter ≤50 nm) deposition patterns at a flow rate ≤25 L/min. Furthermore, numerical studies demonstrated that turbulence dispersion does not significantly affect nanoparticle deposition patterns. This critical review aims to develop the field and increase the state-of-the-art in human lung modelling.
Transient heat transfer and non-isothermal particle-laden gas flows through porous metal foams of differing structure
Publisher: Elsevier BV
Date: 03-2019
Multi-layer PCM solidification in a finned triplex tube considering natural convection
Publisher: Elsevier BV
Date: 08-2017
Intermittent and Nonstationary Drying Technologies
Publisher: CRC Press
Date: 18-09-2017
Entropy Generation Analysis of Natural Convection in a Porous Medium with Casson Fluid using Finite Element Method
Publisher: MDPI AG
Date: 28-07-2023
DOI: 10.20944/PREPRINTS202307.1968.V1
Abstract: This study presents a comprehensive investigation of entropy generation during natural convection in a porous medium with Casson fluid. The governing equations, including the momentum, energy, and entropy balance equations, are solved numerically using finite element method. Through the analysis, various parameters affecting entropy generation are investigated, such as the Casson fluid parameter, Radiation, Prandtl number, and Rayleigh number. The results indicate that the Casson fluid parameter significantly influences the flow and heat transfer characteristics, while the Darcy number and Rayleigh number control the intensity of natural convection. Moreover, the Prandtl number determines the relative significance of heat transfer compared to viscous effects.
Cfd-Mla Analysis of Striking Particle Velocity Magnitude, Particle Diameter, and Impact Time Inside an Acinar Region of Human Lung
Publisher: Elsevier BV
Date: 2022
DOI: 10.2139/SSRN.4100429
Polydisperse Microparticle Transport and Deposition to the Terminal Bronchioles in a Heterogeneous Vasculature Tree
Publisher: Springer Science and Business Media LLC
Date: 06-11-2018
DOI: 10.1038/S41598-018-34804-X
Abstract: The atmospheric particles from different sources, and the therapeutic particles from various drug delivery devices, exhibit a complex size distribution, and the particles are mostly polydisperse. The limited available in vitro , and the wide range of in silico models have improved understanding of the relationship between monodisperse particle deposition and therapeutic aerosol transport. However, comprehensive polydisperse transport and deposition (TD) data for the terminal airways is still unavailable. Therefore, to benefit future drug therapeutics, the present numerical model illustrates detailed polydisperse particle TD in the terminal bronchioles for the first time. Euler-Lagrange approach and Rosin-Rammler diameter distribution is used for polydisperse particles. The numerical results show higher deposition efficiency (DE) in the right lung. Specifically, the larger the particle diameter (d p 5 μm), the higher the DE at the bifurcation area of the upper airways is, whereas for the smaller particle (d p 5 μm), the DE is higher at the bifurcation wall. The overall deposition pattern shows a different deposition hot spot for different diameter particle. These comprehensive lobe-specific polydisperse particle deposition studies will increase understanding of actual inhalation for particle TD, which could potentially increase the efficiency of pharmaceutical aerosol delivery at the targeted position of the terminal airways.
Targeted drug delivery of magnetic nano-particle in the specific lung region
Publisher: MDPI AG
Date: 04-02-2020
DOI: 10.3390/COMPUTATION8010010
Abstract: Aerosolized drug inhalation plays an important role in the treatment of respiratory diseases. All of the published in silico, in vivo, and in vitro studies have improved the knowledge of aerosol delivery in the human respiratory system. However, aerosolized magnetic nano-particle (MNP) transport and deposition (TD) for the specific position of the human lung are still unavailable in the literature. Therefore, this study is aimed to provide an understanding of the magnetic nano-particle TD in the targeted region by imposing an external magnetic field for the development of future therapeutics. Uniform aerosolized nano-particle TD in the specific position of the lung airways will be modelled by adopting turbulence k–ω low Reynolds number simulation. The Euler–Lagrange (E–L) approach and the magneto hydrodynamics (MHD) model are incorporated in the ANSYS fluent (18.0) solver to investigate the targeted nano-particle TD. The human physical activity conditions of sleeping, resting, light activity and fast breathing are considered in this study. The aerosolized drug particles are navigated to the targeted position under the influence of external magnetic force (EMF), which is applied in two different positions of the two-generation lung airways. A numerical particle tracing model is also developed to predict the magnetic drug targeting behavior in the lung. The numerical results reveal that nano-particle deposition efficiency (DE) in two different magnetic field position is different for various physical activities, which could be helpful for targeted drug delivery to a specific region of the lung after extensive clinical trials. This process will also be cost-effective and will minimize unwanted side effects due to systemic drug distribution in the lung.
Steady Natural Convection of Non-Newtonian Power-Law Fluid in a Trapezoidal Enclosure
Publisher: SAGE Publications
Date: 2013
DOI: 10.1155/2013/653108
Abstract: Numerical investigation of free convection heat transfer in a differentially heated trapezoidal cavity filled with non-Newtonian Power-law fluid has been performed in this study. The left inclined surface is uniformly heated whereas the right inclined surface is maintained as uniformly cooled. The top and bottom surfaces are kept adiabatic with initially quiescent fluid inside the enclosure. Finite-volume-based commercial software FLUENT 14.5 is used to solve the governing equations. Dependency of various flow parameters of fluid flow and heat transfer is analyzed including Rayleigh number (Ra) ranging from 10 5 to 10 7 , Prandtl number (Pr) from 100 to 10,000, and power-law index ( n) from 0.6 to 1.4. Outcomes have been reported in terms of isotherms, streamlines, and local Nusselt number for various Ra, Pr, n, and inclined angles. Grid sensitivity analysis is performed and numerically obtained results have been compared with those results available in the literature and were in good agreement.
Transient free convection heat transfer in a section-triangular prismatic enclosure with different aspect ratios
Publisher: Elsevier BV
Date: 05-2019
How severe acute respiratory syndrome coronavirus-2 aerosol propagates through the age-specific upper airways
Publisher: AIP Publishing
Date: 08-2021
DOI: 10.1063/5.0061627
Abstract: The recent outbreak of the COVID-19 causes significant respirational health problems, including high mortality rates worldwide. The deadly corona virus-containing aerosol enters the atmospheric air through sneezing, exhalation, or talking, assembling with the particulate matter, and subsequently transferring to the respiratory system. This recent outbreak illustrates that the severe acute respiratory syndrome (SARS) coronavirus-2 is deadlier for aged people than for other age groups. It is evident that the airway diameter reduces with age, and an accurate understanding of SARS aerosol transport through different elderly people's airways could potentially help the overall respiratory health assessment, which is currently lacking in the literature. This first-ever study investigates SARS COVID-2 aerosol transport in age-specific airway systems. A highly asymmetric age-specific airway model and fluent solver (ANSYS 19.2) are used for the investigation. The computational fluid dynamics measurement predicts higher SARS COVID-2 aerosol concentration in the airway wall for older adults than for younger people. The numerical study reports that the smaller SARS coronavirus-2 aerosol deposition rate in the right lung is higher than that in the left lung, and the opposite scenario occurs for the larger SARS coronavirus-2 aerosol rate. The numerical results show a fluctuating trend of pressure at different generations of the age-specific model. The findings of this study would improve the knowledge of SARS coronavirus-2 aerosol transportation to the upper airways which would thus ameliorate the targeted aerosol drug delivery system.
Unsteady natural convection within a differentially heated enclosure of sinusoidal corrugated side walls
Publisher: Elsevier BV
Date: 10-2012
Lattice Boltzmann simulation of Non-Newtonian power-law fluid flows in a bifurcated channel
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5044333
Improved cooling capacity of a solar heat driven adsorption chiller
Publisher: Elsevier BV
Date: 02-2020
A Comparative Study of Mixed Resolved–Unresolved CFD-DEM and Unresolved CFD-DEM Methods for the Solution of Particle-Laden Liquid Flows
Publisher: Springer Science and Business Media LLC
Date: 07-09-2019
Transition to a chaotic flow in a V-shaped triangular cavity heated from below
Publisher: Elsevier BV
Date: 2019
Two-Layer Red Blood Cell Membrane Model Using the Discrete Element Method
Publisher: Trans Tech Publications, Ltd.
Date: 07-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.846.270
Abstract: The red blood cell (RBC) membrane consists of a lipid bilayer and spectrin-based cytoskeleton, which enclose haemoglobin-rich fluid. Numerical models of RBCs typically integrate the two membrane components into a single layer, preventing investigation of bilayer-cytoskeleton interaction. To address this constraint, a new RBC model which considers the bilayer and cytoskeleton separately is developed using the discrete element method (DEM). This is completed in 2D as a proof-of-concept, with an extension to 3D planned in the future. Resting RBC morphology predicted by the two-layer model is compared to an equivalent and well-established composite (one-layer) model with excellent agreement for critical cell dimensions. A parametric study is performed where area reduction ratio and spring constants are varied. It is found that predicted resting geometry is relatively insensitive to changes in spring stiffness, but a shape variation is observed for reduction ratio changes as expected.
Coupled CFD-DEM simulation of oscillatory particle-laden fluid flow through a porous metal foam heat exchanger: Mitigation of particulate fouling
Publisher: Elsevier BV
Date: 04-2018
Modelling of Red Blood Cell Morphological and Deformability Changes during In-Vitro Storage
Publisher: MDPI AG
Date: 04-05-2020
DOI: 10.3390/APP10093209
Abstract: Storage lesion is a critical issue facing transfusion treatments, and it adversely affects the quality and viability of stored red blood cells (RBCs). RBC deformability is a key indicator of cell health. Deformability measurements of each RBC unit are a key challenge in transfusion medicine research and clinical haematology. In this paper, a numerical study, inspired from the previous research for RBC deformability and morphology predictions, is conducted for the first time, to investigate the deformability and morphology characteristics of RBCs undergoing storage lesion. This study investigates the evolution of the cell shape factor, elongation index and membrane spicule details, where applicable, of discocyte, echinocyte I, echinocyte II, echinocyte III and sphero-echinocyte morphologies during 42 days of in-vitro storage at 4 °C in saline-adenine-glucose-mannitol (SAGM). Computer simulations were performed to investigate the influence of storage lesion-induced membrane structural defects on cell deformability and its recoverability during optical tweezers stretching deformations. The predicted morphology and deformability indicate decreasing quality and viability of stored RBCs undergoing storage lesion. The loss of membrane structural integrity due to the storage lesion further degrades the cell deformability and recoverability during mechanical deformations. This numerical approach provides a potential framework to study the RBC deformation characteristics under varying pathophysiological conditions for better diagnostics and treatments.
Polydisperse Aerosol Transport and Deposition in Upper Airways of Age-Specific Lung
Publisher: MDPI AG
Date: 09-06-2021
Abstract: A comprehensive understanding of airflow characteristics and particle transport in the human lung can be useful in modelling to inform clinical diagnosis, treatment, and management, including prescription medication and risk assessment for rehabilitation. One of the difficulties in clinical treatment of lung disorders lies in the patients’ variable physical lung characteristics caused by age, amongst other factors, such as different lung sizes. A precise understanding of the comparison between different age groups with various flow rates is missing in the literature, and this study aims to analyse the airflow and aerosol transport within the age-specific lung. ANSYS Fluent solver and the large-eddy simulation (LES) model were employed for the numerical simulation. The numerical model was validated with the available literature and the computational results showed airway size-reduction significantly affected airflow and particle transport in the upper airways. This study reports higher deposition at the mouth-throat region for larger diameter particles. The overall deposition efficiency (DE) increased with airway size reduction and flow rate. Lung aging effected the pressure distribution and a higher pressure drop was reported for the aged lung as compared to the younger lung. These findings could inform medical management through in idualised simulation of drug-aerosol delivery processes for the patient-specific lung.
Modeling of mass transfer enhancement in a magnetofluidic micromixer
Publisher: AIP Publishing
Date: 06-2019
DOI: 10.1063/1.5093498
Abstract: The use of magnetism for various microfluidic functions such as separation, mixing, and pumping has been attracting great interest from the research community as this concept is simple, effective, and of low cost. Magnetic control avoids common problems of active microfluidic manipulation such as heat, surface charge, and high ionic concentration. The majority of past works on micromagnetofluidic devices were experimental, and a comprehensive numerical model to simulate the fundamental transport phenomena in these devices is still lacking. The present study aims to develop a numerical model to simulate transport phenomena in microfluidic devices with ferrofluid and fluorescent dye induced by a nonuniform magnetic field. The numerical results were validated by experimental data from our previous work, indicating a significant increase in mass transfer. The model shows a reasonable agreement with experimental data for the concentration distribution of both magnetic and nonmagnetic species. Magnetoconvective secondary flow enhances the transport of nonmagnetic fluorescent dye. A subsequent parametric analysis investigated the effect of the magnetic field strength and nanoparticle size on the mass transfer process. Mass transport of the fluorescent dye is enhanced with increasing field strength and size of magnetic particles.
Nanofluid-based cooling of cylindrical lithium-ion battery packs employing forced air flow
Publisher: Elsevier BV
Date: 07-2017
Molecular basis of transport of surface functionalised gold nanoparticles to pulmonary surfactant
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2RA01892F
Abstract: Molecular-level observations of the behavior of ligand functionalised gold nanoparticles with a lipid monolayers.
Effects of corrugation frequency and aspect ratio on natural convection within an enclosure having sinusoidal corrugation over a heated top surface
Publisher: Elsevier BV
Date: 03-2012
Computational inertial microfluidics: a review.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9LC01022J
Abstract: Schematic illustration of various kinds of geometries used for inertial microfluidics.
Natural convection and heat transfer on a section-triangular roof
Publisher: Elsevier BV
Date: 03-2018
A coupled SPH-DEM approach to model the interactions between multiple red blood cells in motion in capillaries
Publisher: Springer Science and Business Media LLC
Date: 20-11-2016
Effect of Magnetic Field on Double Diffusive Natural Convection Inside a Square Cavity with Isothermal Hollow Insert
Publisher: IOP Publishing
Date: 04-2020
DOI: 10.1088/1757-899X/831/1/012010
Abstract: A numerical study is carried out to analyze both heat and mass transfer phenomena in the presence of an external magnetic field inside a square cavity with an isothermal hollow circular insert located at the centre of the cavity. In the present work, the effects of Hartmann number, Lewis number and buoyancy ratio at constant Rayleigh and Prandtl numbers are investigated simultaneously to understand the importance of these parameters on the characteristics of double diffusive natural convection. Galerkin finite element method is employed for the numerical simulations. Grid sensitivity test and code validation are performed prior to confirm the numerical accuracy of the solution. Quantitative comparison is presented by showing the influence of Hartmann and Lewis numbers for different buoyancy ratios on average Nusselt and Sherwood numbers. It is found that increment of Hartmann number results in lower heat and mass transfer rates. Higher value of Lewis number produces elevated mass transfer rate. However, Lewis number has negative impact on heat transfer rate. Moreover, buoyancy ratio has significant effect on heat and mass transfer inside the cavity.
The steroid mometasone alters protein containing lung surfactant monolayers in a concentration-dependent manner
Publisher: Elsevier BV
Date: 03-2021
DOI: 10.1016/J.JMGM.2021.108084
Abstract: Mometasone is an investigational anti-inflammatory steroidal drug to treat inflammation via pulmonary administration. For steroid drugs to be effective they need to be adsorbed by lung surfactants, a thin monolayer at the air-water interface in alveoli that reduces surface tension. Information on the molecular-level interactions of the drug with lung surfactants is useful to understand the mechanism of adsorption. In this study, we use coarse-grained molecular dynamics simulation to understand the concentration-dependent effect of mometasone on a lung surfactant monolayer (LSM) composed of lipids and surfactant proteins, under two different breathing conditions (exhalation, at surface tension 0 mNm
Transient Free Convection and Heat Transfer in a Partitioned Attic-Shaped Space under Diurnal Thermal Forcing
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 2021
Roll-Back, Extension and Mantle Upwelling Triggered Eocene Potassic Magmatism in NW Iran
Publisher: Oxford University Press (OUP)
Date: 29-06-2018
Drug Meets Monolayer: Understanding the Interactions of Sterol Drugs with Models of the Lung Surfactant Monolayer Using Molecular Dynamics Simulations
Publisher: Springer US
Date: 02-12-2021
DOI: 10.1007/978-1-0716-1843-1_9
Abstract: The lung surfactant monolayer (LSM) is a thin layer of lipids and proteins that forms the air/water interface of the alveoli. The primary function of the LSM is to reduce the surface tension at the air/water interface during breathing. The LSM also forms the main biological barrier for any inhaled particles, including drugs, to treat lung diseases. Elucidating the mechanism by which these drugs bind to and absorb into the LSM requires a molecular-level understanding of any drug-induced changes to the morphology, structure, and phase changes of the LSM.Molecular dynamics simulations have been used extensively to study the structure and dynamics of the LSM. The monolayer is usually simulated in at least two states: the compressed state, mimicking exhalation, and the expanded state, mimicking inhalation. In this chapter, we provide detailed instructions on how to set up, run, and analyze coarse-grained MD simulations to study the concentration-dependent effect of a sterol drug on the LSM, both in the expanded and compressed state.
Heat Transfer Analysis of Viscous Incompressible Fluid by Combined Natural Convection and Radiation in an Open Cavity
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/412480
Abstract: The effect of radiation on natural convection of Newtonian fluid contained in an open cavity is investigated in this study. The governing partial differential equations are solved numerically using the Alternate Direct Implicit method together with the Successive Overrelaxation method. The study is focused on studying the flow pattern and the convective and radiative heat transfer rates are studied for different values of radiation parameters, namely, the optical thickness of the fluid, scattering albedo, and the Planck number. It was found that, in the optically thin limit, an increase in the optical thickness of the fluid raises the temperature and radiation heat transfer of the fluid. However, a further increase in the optical thickness decreases the radiative heat transfer rate due to increase in the energy level of the fluid, which ultimately reduces the total heat transfer rate within the fluid.
Transient air flow and heat transfer due to differential heating on inclined walls and heat source placed on the bottom wall in a partitioned attic shaped space
Publisher: Elsevier BV
Date: 02-2016
Condensation heat transfer and pressure drop characteristics of Isobutane in horizontal channels with twisted tape inserts
Publisher: Elsevier BV
Date: 10-2020
Computational Inertial Microfluidics: Optimal Design for Particle Separation
Publisher: MDPI AG
Date: 16-09-2022
Abstract: Following the emergence of many blood transfusion-associated diseases, novel passive cell separation technologies, such as microfluidic devices, are increasingly designed and optimized to separate red blood cells (RBCs) and white blood cells (WBCs) from whole blood. These systems allow for the rapid diagnosis of diseases without relying on complicated and expensive hematology instruments such as flow microscopes, coagulation analyzers, and cytometers. The inertia effect and the impact of intrinsic hydrodynamic forces, the Dean drag force (FD), and the inertial lift force (FL) on the migration of particles within curved and complex confined channels have been explored theoretically, computationally, and experimentally. This study aimed to optimize the dimensions of a microfluidic channel for fast particle propagation and separation. Several spiral geometries with different cross-sections were tested using computational fluid dynamics (CFD) to separate two particle types representing RBCs and WBCs. The chosen three geometries consist of a single inlet, two outlets, and three spiral turns, each having a different cross-sectional height (120, 135, and 150 µm). Particle separation was successfully achieved in the 135 µm-height microchannel, while other microchannels demonstrated mixed particle types at the outlets.
Topological Optimization of Auxetic Coronary Stents Considering Hemodynamics
Publisher: Frontiers Media SA
Date: 13-09-2021
DOI: 10.3389/FBIOE.2021.728914
Abstract: This paper is to design a new type of auxetic metamaterial-inspired structural architectures to innovate coronary stents under hemodynamics via a topological optimization method. The new architectures will low the occurrence of stent thrombosis (ST) and in-stent restenosis (ISR) associated with the mechanical factors and the adverse hemodynamics. A multiscale level-set approach with the numerical homogenization method and computational fluid dynamics is applied to implement auxetic microarchitectures and stenting structure. A homogenized effective modified fluid permeability (MFP) is proposed to efficiently connect design variables with motions of blood flow around the stent, and a Darcy-Stokes system is used to describe the coupling behavior of the stent structure and fluid. The optimization is formulated to include three objectives from different scales: MFP and auxetic property in the microscale and stenting stiffness in the macroscale. The design is numerically validated in the commercial software MATLAB and ANSYS, respectively. The simulation results show that the new design can not only supply desired auxetic behavior to benefit the deliverability and reduce incidence of the mechanical failure but also improve wall shear stress distribution to low the induced adverse hemodynamic changes. Hence, the proposed stenting architectures can help improve safety in stent implantation, to facilitate design of new generation of stents.
Muco-ciliary clearance: A review of modelling techniques
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.JBIOMECH.2019.109578
Abstract: The airways of the human respiratory system are covered by a protective layer, which is known as airway surface liquid (ASL). This layer consists of two relatively distinct sub-layers a mucus layer (ML), and a periciliary liquid layer (PCL). In addition, the airways are lined with a dense mat of hair-like structures, called cilia, which beat back and forth in a co-ordinated manner and mainly propel the mucus layer. Such interaction between the cilia and mucus is called 'muco-ciliary clearance' (MCC) which is essential to clear the respiratory airways from the inhaled toxic particles deposited on the mucus. The complex nature of lung clearance mechanisms limit the ability to conduct experiments to investigate micro-scale physiological phenomena. As such, modelling techniques are commonly implemented to investigate the effects of biological parameters on the lung muco-ciliary clearance. In the present work, modelling techniques of cilia-ASL interactions - including continuum cilia modelling and discrete cilia modelling - are reviewed and the numerical procedures and level of complexity related to each technique are explained. This is followed by a detailed analysis of the airway surface liquid modelling approaches. In addition, findings of numerical investigations related to the effects of various parameters such as ciliary beat frequency (CBF), mucus rheology, metachronal waves of cilia, surface tension at the PCL-mucus interface, ciliary length, ciliary density, and airway surface liquid depth on the bronchial and tracheal ASL transport are reviewed. This review also explains how these biological parameters can alter the internal power required to perform ciliary beating. Lastly, the main limitations of current numerical works are discussed and significant research directions are brought forward that may be considered in future models to better understand this complex human biological system and its vital clearance mechanism.
Natural convection and heat transfer in attics subject to periodic thermal forcing
Publisher: Elsevier BV
Date: 10-2010
Experimental study of natural convection in a V-shape-section cavity
Publisher: AIP Publishing
Date: 2021
DOI: 10.1063/5.0031104
Abstract: Natural convection in a V-shaped section cavity heated from below and cooled from above is investigated experimentally for the first time in the literature. Temperature measurements using fast-response thermistors and flow visualization using the shadowgraph technology have been performed. The natural convection development in the cavity including the conductional, the transitional, and the fully developed stages is described. It is experimentally proven that the scaling law of the thermal boundary layer thickness is δT ∼ (κt)1/2 and the scaling law of the plume velocity is vp ∼ κRa7/15/l. Furthermore, the occurrence of Hopf bifurcation in the transition to chaos and the flow structure are also identified experimentally. The power spectral density of the temperature time series reveals that the dominant frequency of the oscillations of the unsteady flow depends on the Rayleigh number, which is quantified.
Radiation effects on natural convection laminar flow from a horizontal circular cylinder
Publisher: Informa UK Limited
Date: 06-2011
A coarse-grained red blood cell membrane model to study stomatocyte-discocyteechinocyte morphologies
Publisher: Public Library of Science (PLoS)
Date: 19-04-2019
NATURAL CONVECTION IN A V-SHAPED CAVITY
Publisher: Begellhouse
Date: 2018
SARS CoV-2 aerosol: How far it can travel to the lower airways?
Publisher: AIP Publishing
Date: 06-2021
DOI: 10.1063/5.0053351
Abstract: The recent outbreak of the SARS CoV-2 virus has had a significant effect on human respiratory health around the world. The contagious disease infected a large proportion of the world population, resulting in long-term health issues and an excessive mortality rate. The SARS CoV-2 virus can spread as small aerosols and enters the respiratory systems through the oral (nose or mouth) airway. The SARS CoV-2 particle transport to the mouth–throat and upper airways is analyzed by the available literature. Due to the tiny size, the virus can travel to the terminal airways of the respiratory system and form a severe health hazard. There is a gap in the understanding of the SARS CoV-2 particle transport to the terminal airways. The present study investigated the SARS CoV-2 virus particle transport and deposition to the terminal airways in a complex 17-generation lung model. This first-ever study demonstrates how far SARS CoV-2 particles can travel in the respiratory system. ANSYS Fluent solver was used to simulate the virus particle transport during sleep and light and heavy activity conditions. Numerical results demonstrate that a higher percentage of the virus particles are trapped at the upper airways when sleeping and in a light activity condition. More virus particles have lung contact in the right lung than the left lung. A comprehensive lobe specific deposition and deposition concentration study was performed. The results of this study provide a precise knowledge of the SARs CoV-2 particle transport to the lower branches and could help the lung health risk assessment system.
Numerical investigation of the temporal evolution of particulate fouling in metal foams for air-cooled heat exchangers
Publisher: Elsevier BV
Date: 12-2016
Data-driven modelling techniques for earth-air heat exchangers to reduce energy consumption in buildings: a review
Publisher: Springer Science and Business Media LLC
Date: 30-08-2021
Scaling of Natural Convection of an Inclined Flat Plate: Sudden Cooling Condition
Publisher: ASME International
Date: 11-01-2011
DOI: 10.1115/1.4002982
Abstract: The natural convection boundary layer adjacent to an inclined plate subject to sudden cooling boundary condition has been studied. It is found that the cold boundary layer adjacent to the plate is potentially unstable to Rayleigh–Bénard instability if the Rayleigh number exceeds a certain critical value. A scaling relation for the onset of instability of the boundary layer is achieved. The scaling relations have been developed by equating important terms of the governing equations based on the development of the boundary layer with time. The flow adjacent to the plate can be classified broadly into a conductive, a stable convective, or an unstable convective regime determined by the Rayleigh number. Proper scales have been established to quantify the flow properties in each of these flow regimes. An appropriate identification of the time when the instability may set in is discussed. A numerical verification of the time for the onset of instability is also presented in this study. Different flow regimes based on the stability of the boundary layer have been discussed with numerical results.
Numerical study of nanoscale and microscale particle transport in realistic lung models with and without stenosis
Publisher: Elsevier BV
Date: 12-2021
Scaling of free convection heat transfer in a triangular cavity for Pr> 1
Publisher: Elsevier BV
Date: 10-2011
A novel numerical model to predict the morphological behavior of magnetic liquid marbles using coarse grained molecular dynamics concepts
Publisher: AIP Publishing
Date: 2018
DOI: 10.1063/1.5000289
Abstract: Liquid marbles are liquid droplets coated with superhydrophobic powders whose morphology is governed by the gravitational and surface tension forces. Small liquid marbles take spherical shapes, while larger liquid marbles exhibit puddle shapes due to the dominance of gravitational forces. Liquid marbles coated with hydrophobic magnetic powders respond to an external magnetic field. This unique feature of magnetic liquid marbles is very attractive for digital microfluidics and drug delivery systems. Several experimental studies have reported the behavior of the liquid marbles. However, the complete behavior of liquid marbles under various environmental conditions is yet to be understood. Modeling techniques can be used to predict the properties and the behavior of the liquid marbles effectively and efficiently. A robust liquid marble model will inspire new experiments and provide new insights. This paper presents a novel numerical modeling technique to predict the morphology of magnetic liquid marbles based on coarse grained molecular dynamics concepts. The proposed model is employed to predict the changes in height of a magnetic liquid marble against its width and compared with the experimental data. The model predictions agree well with the experimental findings. Subsequently, the relationship between the morphology of a liquid marble with the properties of the liquid is investigated. Furthermore, the developed model is capable of simulating the reversible process of opening and closing of the magnetic liquid marble under the action of a magnetic force. The scaling analysis shows that the model predictions are consistent with the scaling laws. Finally, the proposed model is used to assess the compressibility of the liquid marbles. The proposed modeling approach has the potential to be a powerful tool to predict the behavior of magnetic liquid marbles serving as bioreactors.
Similarity Solutions for Flow and Heat Transfer of Non-Newtonian Fluid over a Stretching Surface
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/718319
Abstract: Similarity solutions are carried out for flow of power law non-Newtonian fluid film on unsteady stretching surface subjected to constant heat flux. Free convection heat transfer induces thermal boundary layer within a semi-infinite layer of Boussinesq fluid. The nonlinear coupled partial differential equations (PDE) governing the flow and the boundary conditions are converted to a system of ordinary differential equations (ODE) using two-parameter groups. This technique reduces the number of independent variables by two, and finally the obtained ordinary differential equations are solved numerically for the temperature and velocity using the shooting method. The thermal and velocity boundary layers are studied by the means of Prandtl number and non-Newtonian power index plotted in curves.
Magnetic field effect on natural convection and entropy generation in a half-moon shaped cavity with semi-circular bottom heater having different ferrofluid inside
Publisher: Elsevier BV
Date: 06-2016
Natural convection boundary-layer adjacent to an inclined flat plate subject to sudden and ramp heating
Publisher: Elsevier BV
Date: 09-2010
Heat transfer enhancement of modified flat plate heat exchanger
Publisher: Elsevier BV
Date: 03-2021
Ultrafine particle transport and deposition in a large scale 17-generation lung model
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.JBIOMECH.2017.08.028
Abstract: To understand how to assess optimally the risks of inhaled particles on respiratory health, it is necessary to comprehend the uptake of ultrafine particulate matter by inhalation during the complex transport process through a non-dichotomously bifurcating network of conduit airways. It is evident that the highly toxic ultrafine particles damage the respiratory epithelium in the terminal bronchioles. The wide range of in silico available and the limited realistic model for the extrathoracic region of the lung have improved understanding of the ultrafine particle transport and deposition (TD) in the upper airways. However, comprehensive ultrafine particle TD data for the real and entire lung model are still unavailable in the literature. Therefore, this study is aimed to provide an understanding of the ultrafine particle TD in the terminal bronchioles for the development of future therapeutics. The Euler-Lagrange (E-L) approach and ANSYS fluent (17.2) solver were used to investigate ultrafine particle TD. The physical conditions of sleeping, resting, and light activity were considered in this modelling study. A comprehensive pressure-drop along five selected path lines in different lobes was calculated. The non-linear behaviour of pressure-drops is observed, which could aid the health risk assessment system for patients with respiratory diseases. Numerical results also showed that ultrafine particle-deposition efficiency (DE) in different lobes is different for various physical activities. Moreover, the numerical results showed hot spots in various locations among the different lobes for different flow rates, which could be helpful for targeted therapeutical aerosol transport to terminal bronchioles and the alveolar region.
Vapor Compression Cycle: A State-of-the-Art Review on Cycle Improvements, Water and Other Natural Refrigerants
Publisher: MDPI AG
Date: 05-05-2023
DOI: 10.3390/CLEANTECHNOL5020030
Abstract: Air conditioning and refrigeration have become necessary in modern life, accounting for more than 7.8% of greenhouse gases (GHG) emitted globally. Reducing the environmental impact of these systems is crucial for meeting the global GHG emission targets. Two principal directions must be considered to reduce the environmental impact of air conditioning systems. Firstly, reducing the direct effect by looking at less harmful refrigerants and secondly, reducing the indirect effect by searching for options to improve the system efficiency. This study presents the latest developments in the vapor compression cycle and natural refrigerants, focusing on water as a refrigerant. Natural refrigerants, and especially water, could be the ultimate solution for the environmental problems associated with the operation of vapor compression cycle (VCC) cooling systems, including ozone depletion (OD) and global warming (GW). Reducing the environmental impact of building cooling systems is essential, and the recent system improvements made to enhance the system coefficient of performance (COP) are thoroughly discussed in this paper. Though the cycle improvements discussed in this work are essential and could increase the system efficiency, they still need to solve the direct environmental impact of refrigerants. Accordingly, this paper suggests that natural refrigerants, including water, are the most suitable strategic choice to replace the current refrigerants in the refrigeration and air conditioning industry. Finally, this study reviews the latest VCC system improvements and natural refrigerants in order to guide interested researchers with solutions that may reduce the environmental impact of VCC systems and suggest future research areas.
A coupled finite volume & discrete element method to examine particulate foulant transport in metal foam heat exchangers
Publisher: Elsevier BV
Date: 12-2017
Modeling of Multi-Layer Phase Change Material in a Triplex Tube under Various Thermal Boundary Conditions
Publisher: MDPI AG
Date: 09-05-2022
DOI: 10.3390/EN15093465
Abstract: Nowadays, limited energy resources face ever-growing demands of the modern world. One engineering approach to mitigate this problem which has received considerable attention in recent years is using latent heat thermal storage (LHTS) systems, a significant opportunity which is provided by phase change materials (PCMs). In the present study, a numerical investigation was devoted to estimate the simultaneous freezing and melting processes of a double-layer PCM in terms of heat transfer and fluid flow phenomena. A double-pipe cylindrical channel with two compartments, A and B, was considered for locating two PCMs of RT28 and RT35 in various arrangements. The inner and outer walls were exposed to both hot and cold heat transfer fluids (HHTFs and CHTFs, respectively) beginning with solid or liquid initial state, which led to solid–liquid phase change process through PCMs. The numerical simulation was handled by a two-dimensional finite volume method (FVM) with a fixed Rayleigh number of 106 in which conduction and convection heat transfer mechanisms are taken into account. The effects of employing double-layer PCM and their arrangements, inner and outer walls’ boundary conditions, and initial statuses of PCMs are discussed, and the details of the compared results are shown in the form of temperature and liquid fraction variations over time.
Effects of Perforation Geometry on the Heat Transfer Performance of Extended Surfaces
Publisher: Elsevier
Date: 2016
A Computational Study of Chaotic Flow and Heat Transfer within a Trapezoidal Cavity
Publisher: MDPI AG
Date: 28-06-2023
DOI: 10.3390/EN16135031
Abstract: Numerical findings of natural convection flows in a trapezoidal cavity are reported in this study. This study focuses on the shift from symmetric steady to chaotic flow within the cavity. This cavity has a heated bottom wall, a cooled top wall, and adiabatic inclined sidewalls. The unsteady natural convection flows occurring within the cavity are numerically simulated using the finite volume (FV) method. The fluid used in the study is air, and the calculations are performed for different dimensionless parameters, including the Prandtl number (Pr), which is kept constant at 0.71, while varying the Rayleigh numbers (Ra) from 100 to 108 and using a fixed aspect ratio (AR) of 0.5. This study focuses on the effect of the Rayleigh numbers on the transition to chaos. In the transition to chaos, a number of bifurcations occur. The first primary transition is found from the steady symmetric to the steady asymmetric stage, known as a pitchfork bifurcation. The second leading transition is found from a steady asymmetric to an unsteady periodic stage, known as Hopf bifurcation. Another prominent bifurcation happens on the changeover of the unsteady flow from the periodic to the chaotic stage. The attractor bifurcates from a stable fixed point to a limit cycle for the Rayleigh numbers between 4 × 106 and 5 × 106. A spectral analysis and the largest Lyapunov exponents are analyzed to investigate the natural convection flows during the shift from periodic to chaos. Moreover, the cavity’s heat transfers are computed for various regimes. The cavity’s flow phenomena are measured and verified.
Inverse Family of Numerical Methods for Approximating All Simple and Roots with Multiplicity of Nonlinear Polynomial Equations with Engineering Applications
Publisher: Hindawi Limited
Date: 24-12-2021
DOI: 10.1155/2021/3124615
Abstract: A new inverse family of the iterative method is interrogated in the present article for simultaneously estimating all distinct and multiple roots of nonlinear polynomial equations. Convergence analysis proves that the order of convergence of the newly constructed family of methods is two. The computer algebra systems CAS-Mathematica is used to determine the lower bound of convergence order, which justifies the local convergence of the newly developed method. Some nonlinear models from physics, chemistry, and engineering sciences are considered to demonstrate the performance and efficiency of the newly constructed family of inverse simultaneous methods in comparison to classical methods in the literature. The computational time in seconds and residual error graph of the inverse simultaneous methods are also presented to elaborate their convergence behavior.
Thermal Analysis of Magneto-Natural Convection Flows within a Partially Thermally Active Rectangular Enclosure
Publisher: MDPI AG
Date: 31-05-2023
DOI: 10.3390/EN16114462
Abstract: In this study, we numerically investigate heat transfer enhancement in a partially thermally active rectangular enclosure. The enclosure is filled with a ternary hybrid nanofluid (water, Carbon Nanotube, Al2O3, and Graphene). It is subjected to a magnetic field and uniform internal heat generation. The study also investigates the effect of magnetic field strength and direction on the natural convection flow, which arises from density fluctuations caused by partial heating of the left vertical wall. To solve the dimensionless governing equations, the finite element approach is employed. The parameters studied in detail include Rayleigh number (Ra), Hartmann number (Ha), nanoparticle volume fraction (ϕ), and heat generation coefficient (λ). The findings are presented graphically for the range of the parameters as follows: 103≤Ra ≤106, 0≤Ha≤20, 0.01≤ϕ≤0.05, and 0≤λ≤15. It is noted that these parameters have an impact on heat transfer enhancement, flow patterns, and temperature fields. The results show that the average Nusselt number (Nu¯) increases with an increasing value of ϕ. Moreover, it has been noted that Nu¯ decreases as the value of Ha increases, and the impact becomes more obvious at higher Ra values. Finally, the influence of the heat generation coefficient on the heat transfer rate inside an enclosure is examined.
Effect of rotating cylinder on heat transfer in a differentially heated rectangular enclosure filled with power law non-Newtonian fluid
Publisher: Emerald
Date: 08-2016
Abstract: – The purpose of this paper is to numerically investigate two dimensional steady state convective heat transfer in a differentially heated square cavity with constant temperatures and an inner rotating cylinder. The gap between the cylinder and the enclosure walls is filled with power law non-Newtonian fluid. – Finite volume-based CFD software, Fluent (Ansys 15.0) is used to solve the governing equations. Attribution of the various flow parameters of fluid flow and heat transfer are investigated including Rayleigh number, Prandtl number, power law index, the cylinder radius and the angular rotational speed. – Outcomes are reported in terms of isotherms, streamlines and average Nusselt number (Nu) of the heated wall for various considered here. – A detailed investigates is needed in the context of 3D flow. This will be a part of the future work. – The effect of a rotating cylinder on heat transfer and fluid flow in a differentially heated rectangular enclosure filled with power law non-Newtonian fluid has practical importance in the process industry. – The results of this study may be of some interest to the researchers of the field of chemical or process engineers.
Unsteady conjugate heat transfer characteristics in hexagonal cavity equipped with a multi-blade dynamic modulator
Publisher: Elsevier BV
Date: 2023
A thermo-hydraulic characteristics investigation in corrugated plate heat exchanger
Publisher: Elsevier BV
Date: 02-2019
Surface Tension Effects on Flow Dynamics and Alveolar Mechanics in the Acinar Region of Human Lung
Publisher: Elsevier BV
Date: 2022
DOI: 10.2139/SSRN.4102896
A tool to minimize the need of Monte Carlo ray tracing code for 3D finite volume modelling of a standard parabolic trough collector receiver under a realistic solar flux profile
Publisher: Wiley
Date: 27-06-2020
DOI: 10.1002/ESE3.741
Development of empirical equations for irradiance profile of a standard parabolic trough collector using Monte Carlo ray tracing technique
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.860-863.180
Abstract: This article explains a technique in which equations are developed to produce the irradiance profile around the receiver of LS2 collector using a vigorouslyverified MCRT model. A large range of test conditions including daily normal insolation, selective coatings and glass envelop conditions were chosen from the published data by Dudley et al. [1] for the job. The R 2 value is excellent that varies between 0.9857 and 0.9999. Therefore, these equations can be used confidently to produce boundary heat flux profile of the collector at normal incident for conjugate heat transfer analyses of the receiver.
The role of SP-B1-25 peptides in lung surfactant monolayers exposed to gold nanoparticles
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP00268B
Abstract: Lung surfactant monolayer’s (acts as the first line barrier for inhaled nanoparticles) components (lipids and peptides) rearrange themselves by the influence of exposed gold nanoparticles at various stages of the breathing cycle.
Aging effects on airflow distribution and micron-particle transport and deposition in a human lung using CFD-DPM approach
Publisher: Elsevier BV
Date: 08-2021
Natural convection in a triangular enclosure heated from below and non-uniformly cooled from top
Publisher: Elsevier BV
Date: 2015
Natural convection in attics subject to instantaneous and ramp cooling boundary conditions
Publisher: Elsevier BV
Date: 08-2010
Airflow dynamic and particle deposition in age-specific human lungs
Publisher: The University of Queensland
Date: 11-12-2020
DOI: 10.14264/6506E6F
MHD natural convection flow from an isothermal horizontal circular cylinder under consideration of temperature dependent viscosity
Publisher: Emerald
Date: 09-11-2012
DOI: 10.1108/02644401211271636
Abstract: The purpose of this paper is to discuss, with numerical simulations, magnetohydrodynamic (MHD) natural convection laminar flow from an isothermal horizontal circular cylinder immersed in a fluid with viscosity proportional to a linear function of temperature. The governing boundary layer equations are transformed into a non‐dimensional form and the resulting nonlinear system of partial differential equations are reduced to convenient form, which are solved numerically by two very efficient methods: implicit finite difference method together with Keller box scheme and direct numerical scheme. Numerical results are presented by velocity and temperature distributions of the fluid as well as heat transfer characteristics, namely the shearing stress and the local heat transfer rate in terms of the local skin‐friction coefficient and the local Nusselt number for a wide range of MHD parameter, viscosity‐variation parameter and viscous dissipation parameter. MHD flow in this geometry with temperature dependent viscosity is absent in the literature. IN this paper, the results obtained from the numerical simulations have been verified by two methodologies.
Numerical investigation of motion and deformation of a single red blood cell in a stenosed capillary
Publisher: World Scientific Pub Co Pte Lt
Date: 08-2015
DOI: 10.1142/S0219876215400034
Abstract: It is generally assumed that influence of the red blood cells (RBCs) is predominant in blood rheology. The healthy RBCs are highly deformable and can thus easily squeeze through the smallest capillaries having internal diameter less than their characteristic size. On the other hand, RBCs infected by malaria or other diseases are stiffer and so less deformable. Thus it is harder for them to flow through the smallest capillaries. Therefore, it is very important to critically and realistically investigate the mechanical behavior of both healthy and infected RBCs which is a current gap in knowledge. The motion and the steady state deformed shape of the RBCs depend on many factors, such as the geometrical parameters of the capillary through which blood flows, the membrane bending stiffness and the mean velocity of the blood flow. In this study, motion and deformation of a single two-dimensional RBC in a stenosed capillary is explored by using smoothed particle hydrodynamics (SPH) method. An elastic spring network is used to model the RBC membrane, while the RBC's inside fluid and outside fluid are treated as SPH particles. The effect of RBC's membrane stiffness (k b ), inlet pressure (P) and geometrical parameters of the capillary on the motion and deformation of the RBC is studied. The deformation index, RBC's mean velocity and the cell membrane energy are analyzed when the cell passes through the stenosed capillary. The simulation results demonstrate that the k b , P and the geometrical parameters of the capillary have a significant impact on the RBCs' motion and deformation in the stenosed section.
Effect of MHD and heat generation on natural convection flow in an open square cavity under microgravity condition
Publisher: Emerald
Date: 28-12-2012
Numerical study of the transition to chaos of a buoyant plume from a two-dimensional open cavity heated from below
Publisher: Elsevier BV
Date: 09-2018
Pulmonary aerosol transport and deposition analysis in upper 17 generations of the human respiratory tract
Publisher: Elsevier BV
Date: 06-2017
Heat Transfer in Cavities: Configurative Systematic Review
Publisher: MDPI AG
Date: 28-02-2023
DOI: 10.3390/EN16052338
Abstract: This study is a systematic review of research on heat transfer analysis in cavities and aims to provide a comprehensive understanding of flow and heat transfer performance in various kinds of cavities with or without the presence of fins, obstacles, cylinders, and baffles. The study also examines the effects of different forces, such as magnetic force, buoyancy force, and thermophoresis effect on heat transfer in cavities. This study also focuses on different types of fluids, such as air, water, nanofluids, and hybrid nanofluids in cavities. Moreover, this review deals with aspects of flow and heat transfer phenomena for only single-phase flows. It discusses various validation techniques used in numerical studies and the different types and sizes of mesh used by researchers. The study is a comprehensive review of 297 research articles, mostly published since 2000, and covers the current progress in the area of heat transfer analysis in cavities. The literature review in this study shows that cavities with obstacles such as fins and rotating cylinders have a significant impact on enhancing heat transfer. Additionally, it is found that the use of nanofluids and hybrid nanofluids has a greater effect on enhancing heat transfer. Lastly, the study suggests future research directions in the field of heat transfer in cavities. This study’s findings have significant implications for a range of areas, including electronic cooling, energy storage systems, solar thermal technologies, and nuclear reactor systems.
Numerical Study of Mixed Convection and Heat Transfer in Arc-Shaped Cavity with Inner Heat Sources
Publisher: MDPI AG
Date: 12-01-2023
DOI: 10.3390/APP13021029
Abstract: The mixed convection and heat transfer in enclosures with inner heat sources widely exist in building ventilation, cooling of nuclear reactors and cooling of electronic components. In this study, the heat transfer characteristics of mixed convection in an open arc-shaped cavity with double heat sources under the condition of bottom heating and top wall cooling are studied by two-dimensional numerical simulation using ANSYS FLUENT. The influence of the Reynolds number on flow structures, transient characteristics and heat transfer characteristics in the arc cavity was studied by changing inlet wind speed. As the Reynolds number changes from 2.19 × 105 to 4.38 × 107, the flow in the fully developed stage will evolve from turbulent flow to periodic flow and then to steady state flow. In this study, the critical Reynolds number intervals for three different flow states are given. The increase in the Reynolds number enhances the heat convection in the cavity. The difference between heat convection and heat conduction is increased, which has a linear relationship with the Reynolds number. As the Reynolds number increases, the heat removal capacity in the middle region of the double heat sources is not always enhanced, which is due to the sudden change in flow structure and flow state around Re = 1.18 × 107.
Numerical study of turbulent fluid flow and heat transfer in lateral perforated extended surfaces
Publisher: Elsevier BV
Date: 2014
Optimization of fluid characteristics in the main nozzle of an air-jet loom
Publisher: SAGE Publications
Date: 18-08-2021
DOI: 10.1177/00405175211039579
Abstract: As part of the propulsion system, the fluid dynamic features of the main nozzle can immediately affect the stability and efficiency of an air-jet loom. This study aims to optimize the fluid characteristics in the main nozzle of an air-jet loom. To investigate ways of weakening the effect of airflow congestion and backflow phenomenon occurring in the sudden expansion region, the computational fluid dynamics method is employed. Three-dimensional turbulence flow models for a regular main nozzle and 12 prototypes with different nozzle core tip geometry are built, simulated, and analyzed to get the optimum performance. Furthermore, a set of modified equations that consider the direction of airflow are proposed for better estimation of the friction force applied by the nozzle. The result shows that the nozzle core tip's geometry has a significant influence on the internal airflow, affecting the acceleration tube airflow velocity, turbulence intensity, and backflow strength of the sudden expansion region, and other critical fluid characteristics as well. Several proposed models have succeeded in reducing the backflow and outperforming the original design in many different aspects. Models A-60 and C-P, in particular, manage to increase the propulsion force by 37.6% and 20.2% in the acceleration tube while reducing the maximum backflow by 57.1% and 52.2%, respectively. These simulation results can provide invaluable information for the future optimization of the main nozzle.
A review of phase change materials in multi-designed tubes and buildings: Testing methods, applications, and heat transfer enhancement
Publisher: Elsevier BV
Date: 07-2023
Computational fluid dynamics and machine learning algorithms analysis of striking particle velocity magnitude, particle diameter, and impact time inside an acinar region of the human lung
Publisher: AIP Publishing
Date: 10-2022
DOI: 10.1063/5.0106594
Abstract: Complementing computational fluid dynamics (CFD) simulations with machine learning algorithms is becoming increasingly popular as the combination reduces the computational time of the CFD simulations required for classifying, predicting, or optimizing the impact of geometrical and physical variables of a specific study. The main target of drug delivery studies is indicating the optimum particle diameter for targeting particular locations in the lung to achieve a desired therapeutic effect. In addition, the main goal of molecular dynamics studies is to investigate particle–lung interaction through given particle properties. Therefore, this study combines the two by numerically determining the optimum particle diameter required to obtain an ideal striking velocity magnitude (velocity at the time of striking the alveoli, i.e., deposition by sedimentation/diffusion) and impact time (time from release until deposition) inside an acinar part of the lung. At first, the striking velocity magnitudes and time for impact (two independent properties) of three different particle diameters (0.5, 1.5, and 5 μm) are computed using CFD simulations. Then, machine learning classifiers determine the particle diameter corresponding to these two independent properties. In this study, two cases are compared: A healthy acinus where a surfactant layer covers the inner surface of the alveoli providing low air–liquid surface tension values (10 mN/m), and a diseased acinus where only a water layer covers the surface causing high surface tension values (70 mN/m). In this study, the airflow velocity throughout the breathing cycle corresponds to a person with a respiratory rate of 13 breaths per minute and a volume flow rate of 6 l/min. Accurate machine learning results showed that all three particle diameters attain larger velocities and smaller impact times in a diseased acinus compared to a healthy one. In both cases, the 0.5-μm particles acquire the smallest velocities and longest impact times, while the 1.5-μm particles possess the largest velocities and shortest impact times.
A macroscopic particle modelling approach for non-isothermal solid-gas and solid-liquid flows through porous media
Publisher: Elsevier BV
Date: 11-2019
The Effect of Temperature Dependent Viscosity on MHD Natural Convection Flow from an Isothermal Sphere
Publisher: Academic World Research
Date: 04-2012
Numerical simulations of particle deposition in metal foam heat exchangers
Publisher: World Scientific Pub Co Pte Lt
Date: 12-2013
DOI: 10.1142/S2047684113500164
Abstract: Australia is a high-potential country for geothermal power with reserves currently estimated in the tens of millions of petajoules, enough to power the nation for at least 1000 years at current usage. However, these resources are mainly located in isolated arid regions where water is scarce. Therefore, wet cooling systems for geothermal plants in Australia are the least attractive solution and thus air-cooled heat exchangers are preferred. In order to increase the efficiency of such heat exchangers, metal foams have been used. One issue raised by this solution is the fouling caused by dust deposition. In this case, the heat transfer characteristics of the metal foam heat exchanger can dramatically deteriorate. Exploring the particle deposition property in the metal foam exchanger becomes crucial. This paper is a numerical investigation aimed to address this issue. Two-dimensional (2D) numerical simulations of a standard one-row tube bundle wrapped with metal foam in cross-flow are performed and highlight preferential particle deposition areas.
Impacts of Rotation on Unsteady Fluid Flow and Energy Distribution through a Bending Duct with Rectangular Cross Section
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 2022
A Novel Experimental Method to Assess Particle Deposition in Idealized Porous Channels
Publisher: Informa UK Limited
Date: 13-09-2017
Airflow and particle transport prediction through stenosis airways
Publisher: MDPI AG
Date: 10-02-2020
Abstract: Airflow and particle transport in the human lung system is influenced by biological and other factors such as breathing pattern, particle properties, and deposition mechanisms. Most of the studies to date have analyzed airflow characterization and aerosol transport in idealized and realistic models. Precise airflow characterization for airway stenosis in a digital reference model is lacking in the literature. This study presents a numerical simulation of airflow and particle transport through a stenosis section of the airway. A realistic CT-scan-based mouth–throat and upper airway model was used for the numerical calculations. Three different models of a healthy lung and of airway stenosis of the left and right lung were used for the calculations. The ANSYS FLUENT solver, based on the finite volume discretization technique, was used as a numerical tool. Proper grid refinement and validation were performed. The numerical results show a complex-velocity flow field for airway stenosis, where airflow velocity magnitude at the stenosis section was found to be higher than that in healthy airways. Pressure drops at the mouth–throat and in the upper airways show a nonlinear trend. Comprehensive pressure analysis of stenosis airways would increase our knowledge of the safe mechanical ventilation of the lung. The turbulence intensities at the stenosis sections of the right and left lung were found to be different. Deposition efficiency (DE) increased with flow rate and particle size. The findings of the present study increase our understanding of airflow patterns in airway stenosis under various disease conditions. More comprehensive stenosis analysis is required to further improve knowledge of the field.
Surface Tension Effects on Flow Dynamics and Alveolar Mechanics in the Acinar Region of Human Lung
Publisher: Elsevier BV
Date: 2022
DOI: 10.2139/SSRN.4074510
The concentration-dependent effect of hydrocortisone on the structure of model lung surfactant monolayer by using an in silico approach
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2RA05268G
Abstract: Adsorption mechanism of corticosteroid drug hydrocortisone in the lung surfactant monolayer.
Unsteady Natural Convection Within a Porous Enclosure of Sinusoidal Corrugated Side Walls
Publisher: Springer Science and Business Media LLC
Date: 07-06-2014
Transition to an unsteady flow induced by a fin on the sidewall of a differentially heated air-filled square cavity and heat transfer
Publisher: Elsevier BV
Date: 04-2014
Conjugate natural convection in a corrugated solid partitioned differentially heated square cavity
Publisher: Informa UK Limited
Date: 13-08-2020
Phenolic compounds alter the ion permeability of phospholipid bilayers via specific lipid interactions
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CP03250J
Abstract: How phenolic compounds interact with biological membranes and alter the menbrane properties.
Turbulent dense gas flow characteristics in swirling conical diffuser
Publisher: Elsevier BV
Date: 06-2017
Deposition of Smoke Particles in Human Airways with Realistic Waveform
Publisher: MDPI AG
Date: 15-07-2021
Abstract: Exposure to toxic particles from smoke generated either from bush fire, stable burning, or direct smoking is very harmful to our health. The tiny particles easily penetrate deep into the lungs after exposure and damage the airways. Tobacco smoking causes the direct emission of 2.6 million tons of CO2 and 5.2 million tons of methane annually into the atmosphere. Nevertheless, it is one of the significant contributors to various respiratory diseases leading to lung cancer. These particles’ deposition in the human airway is computed in the present article for refining our understanding of the adverse health effects due to smoke particle inhalation, especially cigarette smoke. Until recently, little work has been reported to account for the transient flow pattern of cigarette smoking. Consideration of transient flow may change the deposition pattern of the particle. A high-resolution CT scan image of the respiratory tract model consisting of the oral cavity, throat, trachea, and first to sixth generations of the lungs helps predict cigarette smoke particle (CSP) deposition. With the same scan, a realistic geometric model of the human airways of an adult subject is used to simulate the transport of air and particle. The CSP deposition is determined at different locations from the oral cavity to the sixth generation of the bronchi. In addition, an unsteady breathing curve indicative of realistic smoking behavior is utilized to represent the breathing conditions accurately. The discrete phase model (DPM) technique is used to determine smoke particle deposition in the human airways. It is found that the deposition increases with the size of the smoke particle. Particles tend to deposit in the oral cavity around the bifurcation junction of the airways. The deposition fraction of CSP with the realistic waveform of smoking is found to be smaller compared to that during the stable flow condition. It is also observed that the fine particles (0.1–1.0 micron) escape to lower generations, leading to higher deposition of fine particles in the deeper airways. The outcome of the study is helpful for understanding smoke-related pulmonary complications.
Transition to unsteady natural convection flow in a prismatic enclosure of triangular section
Publisher: Elsevier BV
Date: 2017
Natural convection in attic-shaped spaces subject to sudden and ramp heating boundary conditions
Publisher: Springer Science and Business Media LLC
Date: 13-05-2010
Computational Fluid Dynamics Analysis of Spray Cooling in Australia
Publisher: MDPI AG
Date: 12-07-2023
DOI: 10.3390/EN16145317
Abstract: Spray cooling technology offers high levels of uniform heat removal with very low fluid volumes and has found recent application in relatively small-scale use cases. Since it is a complex process, research can enable spray cooling to be applied more widely and at larger scales, such as in HVAC, as a means to operate more efficiently. Weather conditions are one of the main parameters that directly affect the effectiveness of spray cooling. This study investigates the spray cooling performance for temperature and humidity conditions in six Australian cities. ANSYS Fluent (2021 R1) software is applied for the numerical simulation. The numerical model is first validated with the available literature before a numerical simulation is conducted to assess each city throughout the year. These include Adelaide, Brisbane, Darwin, Melbourne, Perth, and Sydney. The spray cooling pattern, temperature, and humidity distribution, as well as the evaporation effect on different regions in Australia, is simulated and analysed based on the CFD technique. The results from this study indicate that weather conditions influence spray cooling for all cities, especially in summer. Along the wind tunnel, the temperature significantly drops at the spray cooling area, while the humidity increases. Due to the effect of spray cooling inside the wind tunnel, the temperature at the outlet is still lower than the inlet for all cases. However, the humidity at the outlet is higher than the inlet for all cases.
Multiple-relaxation-time lattice Boltzmann simulation of natural convection flow in a partitioned cavity using GPU computing
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5115862
Solid-liquid phase change investigation through a double pipe heat exchanger dealing with time-dependent boundary conditions
Publisher: Elsevier BV
Date: 2018
An improved boundary layer scaling with ramp heating on a sloping plate
Publisher: Elsevier BV
Date: 04-2012
Recent advances in lung-on-a-chip models.
Publisher: Elsevier BV
Date: 09-2022
DOI: 10.1016/J.DRUDIS.2022.06.004
Abstract: With the global burden of respiratory diseases, rapid identification of the best therapeutic measures to combat these diseases is essential. Animal models and 2D cell culture models do not replicate the findings observed in vivo. To gain deeper insight into lung pathology and physiology, 3D and advanced lung-on-a-chip models have been developed recently. Lung-on-a-chip models more accurately simulate the lung's microenvironment and functions in vivo, resulting in more-accurate assessments of drug safety and effectiveness. This review discusses the transition from 2D to 3D models and the recent advances in lung-on-a-chip platforms, their implementation and the numerous challenges faced. Finally, a general overview of this platform and its potential applications in respiratory disease research and drug discovery is highlighted.
SPH-DEM approach to numerically simulate the deformation of three-dimensional RBCs in non-uniform capillaries
Publisher: Springer Science and Business Media LLC
Date: 12-2016
Hydrogen production with a photovoltaic thermal system enhanced by phase change materials, Shiraz, Iran case study
Publisher: Elsevier BV
Date: 04-2019
Lattice Boltzmann Simulation of Magnetic Field Effect on Electrically Conducting Fluid at Inclined Angles in Rayleigh-B閚ard Convection
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 2021
Pressure-Induced Instability Characteristics of a Transient Flow and Energy Distribution through a Loosely Bent Square Duct
Publisher: Computers, Materials and Continua (Tech Science Press)
Date: 2022
Scaling Analysis of the Unsteady Natural Convection Boundary Layer Adjacent to an Inclined Plate for Pr > 1 Following Instantaneous Heating
Publisher: ASME International
Date: 31-08-2011
DOI: 10.1115/1.4004336
Abstract: The unsteady natural convection boundary layer adjacent to an instantaneously heated inclined plate is investigated using an improved scaling analysis and direct numerical simulations. The development of the unsteady natural convection boundary layer following instantaneous heating may be classified into three distinct stages including a start-up stage, a transitional stage, and a steady state stage, which can be clearly identified in the analytical and numerical results. Major scaling relations of the velocity and thicknesses and the flow development time of the natural convection boundary layer are obtained using triple-layer integral solutions and verified by direct numerical simulations over a wide range of flow parameters.
Natural convection and heat transfer in a valley shaped cavity filled with initially stratified water
Publisher: Elsevier BV
Date: 06-2018
Periodically Forced Natural Convection Through the Roof of an Attic-Shaped Building
Publisher: InTech
Date: 17-10-2011
DOI: 10.5772/20296
A review of natural convection and heat transfer in attic-shaped space
Publisher: Elsevier BV
Date: 10-2011
CFD Study of Dry Pulmonary Surfactant Aerosols Deposition in Upper 17 Generations of Human Respiratory Tract
Publisher: MDPI AG
Date: 02-05-2022
Abstract: The efficient generation of high concentrations of fine-particle, pure surfactant aerosols provides the possibility of new, rapid, and effective treatment modalities for Acute Respiratory Distress Syndrome (ARDS). SUPRAER-CATM is a patented technology by Kaer BiotherapeuticsTM, which is a new class of efficient aerosol drug generation and delivery system using Compressor Air (CA). SUPRAER-CA is capable of aerosolizing relatively viscous solutions or suspensions of proteins and surfactants and of delivering them as pure fine particle dry aerosols. In this Computational Fluid Dynamics (CFD) study, we select a number of sites within the upper 17 generations of the human respiratory tract for calculation of the deposition of dry pulmonary surfactant aerosol particles. We predict the percentage of inhaled dry pulmonary surfactant aerosol arriving from the respiratory bronchioles to the terminal alveolar sacs. The dry pulmonary surfactant aerosols, with a Mass Median Aerodynamic Diameter (MMAD) of 2.6 µm and standard deviation of 1.9 µm, are injected into the respiratory tract at a dry surfactant aerosol flow rate of 163 mg/min to be used in the CFD study at an air inhalation flow rate of 44 L/min. This CFD study in the upper 17th generation of a male adult lung has shown computationally that the penetration fraction (PF) is approximately 25% for the inhaled surfactant aerosols. In conclusion, an ARDS patient might receive approximately one gram of inspired dry surfactant aerosol during an administration period of one hour as a possible means of further inflating partly collapsed alveoli.
On the effect of Reynolds number for flow past three side-by-side square cylinders for unequal gap spacings
Publisher: Springer Science and Business Media LLC
Date: 17-10-2014
Two- and four-way coupling of cohesive poly-disperse particulate foulants on a metal foam fibre immersed in quiescent fluid
Publisher: Elsevier BV
Date: 12-2017
Transitional free convection flow and heat transfer within attics in cold climate
Publisher: National Library of Serbia
Date: 2022
Abstract: The transitional free convection flow and heat transfer within attics in cold climate are investigated using 3-D numerical simulations for a range of Rayleigh numbers from 103 to 106 and height-length ratios from 0.1 to 1.5. The development process of free convection in the attic could be classified into three-stages: an initial stage, a transitional stage, and a fully developed stage. Flow structures in different stages including transverse and longitudinal rolls are critically analyzed in terms of the location and strength of convection rolls and their impacts on the heat transfer. The transition unsteady flow and asymmetry flow in the fully developed stage is discussed for the fixed height-length ratio 0.5. Various flow regimes are given in a bifurcation diagram in the parameter space of Rayleigh numbers (102 Ra 107) for height-length ratios (0.1 A 1.5). The time series of heat transfer rate through the bottom wall is quantified for different height-length ratios. The overall heat transfer rate for the low Prandtl fluid (Pr = 0.7) could be enhanced based on 3-D flow structure.
Mixed Convection Over a Horizontal Plate With Streamwise Non-Uniform Surface Temperature Distribution
Publisher: ASME International
Date: 06-06-2013
DOI: 10.1115/1.4023745
Abstract: Numerical investigation on mixed convection of a two-dimensional incompressible laminar flow over a horizontal flat plate with streamwise sinusoidal distribution of surface temperature has been performed for different values of Rayleigh number, Reynolds number and frequency of periodic temperature for constant Prandtl number and litude of periodic temperature. Finite element method adapted to rectangular nonuniform mesh elements by a nonlinear parametric solution algorithm basis numerical scheme has been employed. The investigating parameters are the Rayleigh number, the Reynolds number and frequency of periodic temperature. The effect of variation of in idual investigating parameters on mixed convection flow characteristics has been studied to observe the hydrodynamic and thermal behavior for while keeping the other parameters constant. The fluid considered in this study is air with Prandtl number 0.72. The results are obtained for the Rayleigh number range of 102 to 104, Reynolds number ranging from 1 to 100 and the frequency of periodic temperature from 1 to 5. Isotherms, streamlines, average and local Nusselt numbers are presented to show the effect of the different values of aforementioned investigating parameters on fluid flow and heat transfer.
Molecular insights on the interference of simplified lung surfactant models by gold nanoparticle pollutants
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.BBAMEM.2019.06.001
Abstract: Inhaled nanoparticles (NPs) are experienced by the first biological barrier inside the alveolus known as lung surfactant (LS), a surface tension reducing agent, consisting of phospholipids and proteins in the form of the monolayer at the air-water interface. The monolayer surface tension is continuously regulated by the alveolus compression and expansion and protects the alveoli from collapsing. Inhaled NPs can reach deep into the lungs and interfere with the biophysical properties of the lung components. The interaction mechanisms of bare gold nanoparticles (AuNPs) with the LS monolayer and the consequences of the interactions on lung function are not well understood. Coarse-grained molecular dynamics simulations were carried out to elucidate the interactions of AuNPs with simplified LS monolayers at the nanoscale. It was observed that the interactions of AuNPs and LS components deform the monolayer structure, change the biophysical properties of LS and create pores in the monolayer, which all interfere with the normal lungs function. The results also indicate that AuNP concentrations >0.1 mol% (of AuNPs/lipids) hinder the lowering of the LS surface tension, a prerequisite of the normal breathing process. Overall, these findings could help to identify the possible consequences of airborne NPs inhalation and their contribution to the potential development of various lung diseases.
Flow boiling heat transfer and pressure drop characteristics of Isobutane in horizontal channels with twisted tapes
Publisher: Elsevier BV
Date: 12-2020
A method of three-dimensional thermo-fluid simulation of the receiver of a standard parabolic trough collector
Publisher: Springer Singapore
Date: 04-10-2018
Heat transfer augmentation in retrofitted corrugated plate heat exchanger
Publisher: Elsevier BV
Date: 11-2020
Heat transfer enhancement in a baffled attic-shaped space
Publisher: Springer Singapore
Date: 04-10-2018
Shear Thinning and Shear Thickening Non- Newtonian Confined Fluid Flow over Rotating Cylinder
Publisher: Scientific and Academic Publishing
Date: 07-01-2013
Double Diffusive Marangoni Convection Flow of Electrically Conducting Fluid in a Square Cavity With Chemical Reaction
Publisher: ASME International
Date: 07-03-2014
DOI: 10.1115/1.4026372
Abstract: Double diffusive Marangoni convection flow of viscous incompressible electrically conducting fluid in a square cavity is studied in this paper by taking into consideration of the effect of applied magnetic field in arbitrary direction and the chemical reaction. The governing equations are solved numerically by using alternate direct implicit (ADI) method together with the successive over relaxation (SOR) technique. The flow pattern with the effect of governing parameters, namely the buoyancy ratio W, diffusocapillary ratio w, and the Hartmann number Ha, is investigated. It is revealed from the numerical simulations that the average Nusselt number decreases whereas the average Sherwood number increases as the orientation of magnetic field is shifted from horizontal to vertical. Moreover, the effect of buoyancy due to species concentration on the flow is stronger than the one due to thermal buoyancy. The increase in diffusocapillary parameter, w causes the average Nusselt number to decrease, and average Sherwood number to increase.
Scaling for the Prandtl number of the natural convection boundary layer of an inclined flat plate under uniform surface heat flux
Publisher: Elsevier BV
Date: 04-2012
GPU Accelerated Multiple-Relaxation-Time Lattice Boltzmann Simulation of Convective Flows in a Porous Media
Publisher: Frontiers Media SA
Date: 05-11-2018
The effect of thermal radiation on the natural convection boundary layer flow over a wavy horizontal surface
Publisher: Elsevier BV
Date: 10-2014
Computational Modelling of the Interaction of Gold Nanoparticle with Lung Surfactant Monolayer
Publisher: Springer Science and Business Media LLC
Date: 04-02-2019
DOI: 10.1557/ADV.2019.93
Numerical Study of Flow Through a Reducer for Scale Growth Suppression
Publisher: Elsevier
Date: 2016
Scaling of natural convection of an inclined flat plate: Ramp cooling condition
Publisher: Elsevier BV
Date: 11-2010
CFD simulations of flow and heat transfer through the porous interface of a metal foam heat exchanger
Publisher: American Society of Mechanical Engineers
Date: 28-07-2014
Abstract: This paper offers numerical modelling of a waste heat recovery system. A thin layer of metal foam is attached to a cold plate to absorb heat from hot gases leaving the system. The heat transferred from the exhaust gas is then transferred to a cold liquid flowing in a secondary loop. Two different foam PPI (Pores Per Inch) values are examined over a range of fluid velocities. Numerical results are then compared to both experimental data and theoretical results available in the literature. Challenges in getting the simulation results to match those of the experiments are addressed and discussed in detail. In particular, interface boundary conditions specified between a porous layer and a fluid layer are investigated. While physically one expects much lower fluid velocity in the pores compared to that of free flow, capturing this sharp gradient at the interface can add to the difficulties of numerical simulation. The existing models in the literature are modified by considering the pressure gradient inside and outside the foam. Comparisons against the numerical modelling are presented. Finally, based on experimentally-validated numerical results, thermo-hydraulic performance of foam heat exchangers as waste heat recovery units is discussed with the main goal of reducing the excess pressure drop and maximising the amount of heat that can be recovered from the hot gas stream.
Computational evaluation of drug delivery in human respiratory tract under realistic inhalation
Publisher: AIP Publishing
Date: 08-2021
DOI: 10.1063/5.0053980
Abstract: In recent years, pulmonary diseases have posed severe health problems because of increasing air pollution. Some of the promising drug delivery devices for administering the active pharmaceutical ingredients through the pulmonary route include a pressurized metered-dose inhaler and dry powder inhaler (DPI) for the management of respiratory illness. The drug settling (deposition) efficiency in different regions of a human respiratory tract (HRT) for different drug particle sizes is computed using the discrete phase model in the current study. A computer tomography-based realistic HRT replica is used for this purpose with different inhalation rates following a realistic inhalation profile through the DPI device. Unsteady flow analysis is carried out in a human respiratory system up to the sixth-generation bronchi. The particle force balance equation is used in the discrete-phase model to simulate the motion of drug particles in the HRT. Low, moderate, and high inhalation rates following realistic inhalation profiles are used in the present study. The particles of larger size are deposited more in the oral cavity and are deposited higher at a higher inhalation rate due to higher inertia force. It is also observed that drug particle size plays a key role in drug delivery through dry powder inhalers. It is also found that drugs should contain smaller-sized particles (called fine particles) to enable their reach in the distal bronchi.
Concentration-dependent cortisone adsorption and interaction with model lung surfactant monolayer
Publisher: Informa UK Limited
Date: 23-08-2022
Natural Convection Flow with Surface Radiation Along a Vertical Wavy Surface
Publisher: Informa UK Limited
Date: 09-2013
Characteristic-Based Fluid Flow Modeling between Two Eccentric Cylinders in Laminar and Turbulent Regimes
Publisher: Hindawi Limited
Date: 29-04-2022
DOI: 10.1155/2022/8265671
Abstract: Determining the flow between eccentric cylinders is crucial in a wide range of industries. The governing equations for the flow between eccentric cylinders cannot be solved analytically. Therefore, three-dimensional incompressible viscous fluid flow between eccentric and concentric cylinders has numerically been simulated in this paper to investigate them using a characteristic-based approach. The first-order characteristic-based scheme is used to calculate convective terms, whereas the second-order averaging technique is used to calculate viscous fluxes. The Taylor number, eccentricity distance, Reynolds number, and radius ratio are considered the controlling parameters of fluid flow between the cylinders. The influence of flow between cylinders on flow patterns is presented in terms of velocity, pressure, and flow contours. It is found that at a constant Taylor number, the asymmetric centrifugal forces produce the Taylor vortices on the right of the internal rotating cylinder as the eccentric distance increases. When the eccentric distance increases, the magnitude of shear stress and its fluctuation on the cylinder wall, as well as the pressure on the cylinder wall, rise. The numerical results obtained were validated by comparing them to previously published experimental results, which showed a high level of agreement.
Shape matters-the interaction of gold nanoparticles with model lung surfactant monolayers
Publisher: The Royal Society
Date: 10-2021
Abstract: The lung surfactant monolayer (LSM) forms the main biological barrier for any inhaled particles to enter our bloodstream, including gold nanoparticles (AuNPs) present as air pollutants and under investigation for use in biomedical applications. Understanding the interaction of AuNPs with lung surfactant can assist in understanding how AuNPs enter our lungs. In this study, we use coarse-grained molecular dynamics simulations to investigate the effect of four different shape D AuNPs (spherical, box, icosahedron and rod) on the structure and dynamics of a model LSM, with a particular focus on differences resulting from the shape of the AuNP. Monolayer-AuNP systems were simulated in two different states: the compressed state and the expanded state, representing inhalation and exhalation conditions, respectively. Our results indicate that the compressed state is more affected by the presence of the AuNPs than the expanded state. Our results show that in the compressed state, the AuNPs prevent the monolayer from reaching the close to zero surface tension required for normal exhalation. In the compressed state, all four nanoparticles (NPs) reduce the lipid order parameters and cause a thinning of the monolayer where the particles drag surfactant molecules into the water phase. Comparing the different properties shows no trend concerning which shape has the biggest effect on the monolayer, as shape-dependent effects vary among the different properties. Insights from this study might assist future work of how AuNP shapes affect the LSM during inhalation or exhalation conditions.
Scaling analysis and numerical simulation of natural convection from a duct
Publisher: Informa UK Limited
Date: 02-09-2017
Natural convection from a Plane Vertical Porous Surface in Non Isothermal
Publisher: Vilnius University Press
Date: 25-04-2004
DOI: 10.15388/NA.2004.9.2.15164
Abstract: In this paper, laminar natural convection flow from a permeable and isothermal vertical surface placed in non-isothermal surroundings is considered. Introducing appropriate transformations into the boundary layer equations governing the flow derives non-similar boundary layer equations. Results of both the analytical and numerical solutions are then presented in the form of skin-friction and Nusselt number. Numerical solutions of the transformed non-similar boundary layer equations are obtained by three distinct solution methods, (i) the perturbation solutions for small ξ (ii) the asymptotic solution for large ξ (iii) the implicit finite difference method for all ξ where ξ is the transpiration parameter. Perturbation solutions for small and large values of ξ are compared with the finite difference solutions for different values of pertinent parameters, namely, the Prandtl number Pr, and the ambient temperature gradient n.
Concentration-Dependent Effect of the Steroid Drug Prednisolone on a Lung Surfactant Monolayer
Publisher: American Chemical Society (ACS)
Date: 28-03-2022
DOI: 10.1021/ACS.LANGMUIR.1C02817
Abstract: The lung surfactant monolayer (LSM) is the main barrier for particles entering the lung, including steroid drugs used to treat lung diseases. The present study combines Langmuir experiments and coarse-grained (CG) molecular dynamics simulations to investigate the concentration-dependent effect of steroid drug prednisolone on the structure and morphology of a model LSM. The surface pressure-area isotherms for the Langmuir monolayers reveal a concentration-dependent decrease in area per lipid (APL). Results from simulations at a fixed surface tension, representing inhalation and exhalation conditions, suggest that at high drug concentrations, prednisolone induces a collapse of the LSM, which is likely caused by the inability of the drug to diffuse into the bilayer. Overall, the monolayer is most susceptible to drug-induced collapse at surface tensions representing exhalation conditions. The presence of cholesterol also exacerbates the instability. The findings of this investigation might be helpful for better understanding the interaction between steroid drug prednisolone and lung surfactants in relation to off-target effects.
A Computational Study on Fluid Flow and Heat Transfer Through a Rotating Curved Duct with Rectangular Cross Section
Publisher: International Information and Engineering Technology Association
Date: 31-08-2021
DOI: 10.18280/IJHT.390419
Abstract: The understanding of fluid flow and heat transfer (HT) through a rotating curved duct (RCD) is important for different engineering applications. The available literature improved the understanding of the fluid flow and HT through a large-curvature rotating duct. However, the comprehensive knowledge of fluid flow and HT through an RCD with small curvature is little known. This numerical study aims to perform fluid flow characterization and HT through an RCD with curvature ratio 0.001. The spectral based numerical approach investigates the effects of rotation on fluid flow and HT for the Taylor number −1000≤Tr≤1500. A constant pressure gradient force, the Dean number Dn = 100, and a constant buoyancy force parameter, the Grashof number Gr = 500 are used for the numerical simulation. Fortran code is developed for the numerical computations and Tecplot software is used for the post-processing purpose. The numerical study investigates steady solutions and a structure of two-branches of steady solutions is obtained for positive rotation. The transient solution reports the transitional flow patterns and HT through the rotating duct, and two- to four-vortex solutions are observed. In case of negative rotation, time-dependent solutions show that the Coriolis force exhibits an opposite effect to that of the curvature so that the flow characteristics exhibit various flow instabilities. The numerical result shows that convective HT is increased with the increase of rotation and highly complex secondary flow patterns influence the overall HT from the heated wall to the fluid. To validate the numerical results, a comparison with the experimental data is provided, which shows that a good agreement is attained between the numerical and experimental investigations.
Theoretical study on the performance of a solar still system integrated with PCM-PV module for sustainable water and power generation
Publisher: Elsevier BV
Date: 10-2018
Natural Convection Flow with Combined Buoyancy Effects Due to Thermal and Mass Diffusion in a Thermally Stratified Media
Publisher: Vilnius University Press
Date: 25-01-2004
DOI: 10.15388/NA.2004.9.1.15173
Abstract: We present here a numerical study of laminar doubly diffusive free convection flows adjacent to a vertical surface in a stable thermally stratified medium. The governing equations of mass, momentum, energy and species are non-dimensionalized. These equations have been solved by using an implicit finite difference method and local non-similarity method. The results show many interesting aspects of complex interaction of the two buoyant mechanisms that have been shown in both the tabular as well as graphical form.
Analysis of particle-laden fluid flows, tortuosity and particle-fluid behaviour in metal foam heat exchangers
Publisher: Elsevier BV
Date: 11-2017
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