ORCID Profile
0000-0003-3483-3759
Current Organisations
University of New South Wales
,
ANSTO
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Artificial Intelligence and Image Processing | Interdisciplinary Engineering | Heat and Mass Transfer Operations | Simulation And Modelling | Numerical Computation | Neural Networks, Genetic Alogrithms And Fuzzy Logic | Computer Software Not Elsewhere Classified | Computer Software | Functional Materials | Other Information, Computing And Communication Sciences | Fluid Physics | Numerical Analysis | Systems engineering | Building Not Elsewhere Classified | Sensor Technology (Chemical aspects) | Heat And Mass Transfer Operations | Nanomaterials | Nanotechnology | Functional materials | Stochastic Analysis And Modelling | Nanotechnology | Materials Engineering | Biomedical Engineering Not Elsewhere Classified | Medical And Health Sciences Not Elsewhere Classified | Composite and Hybrid Materials | Electrochemical energy storage and conversion | Medical Devices | Interdisciplinary Engineering not elsewhere classified | Statistics | Structural Engineering | Biomechanical Engineering | Numerical Analysis | Civil Engineering | Nanomaterials | Civil engineering | Computational Heat Transfer | Mathematical Sciences Not Elsewhere Classified | Engineering Practice | Clinical Sciences Not Elsewhere Classified | Carbon sequestration science | Fire safety engineering
Computer software and services not elsewhere classified | Expanding Knowledge in Engineering | Application packages | Physical sciences | Mathematical sciences | Cardiovascular system and diseases | Expanding Knowledge in Built Environment and Design | Expanding Knowledge in Technology | Other | Civil Construction Design | Housing | Building Management and Services not elsewhere classified | Housing | Respiratory system and diseases (incl. asthma) | Health and support services not elsewhere classified | Manufactured products not elsewhere classified | Nuclear | Residential Energy Conservation and Efficiency | Diagnostic Methods | Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Biological Sciences | Health Status (e.g. Indicators of Well-Being) |
Publisher: MDPI AG
Date: 09-04-2019
DOI: 10.3390/APP9071486
Abstract: The steam ejector is a core component of an ejector-based refrigeration system. Additionally, steam ejectors can also be potentially applied for a fire suppression system by using pressurized steam droplets to rapidly quench and extinguish the fire. The use of steam will significantly reduce the amount of water consumption and pipe flow rate compared to conventional sprinklers. However, the efficiency of the steam ejector nozzle is one of major factors that can influence the extinguishing mechanisms and the performance of pressurized steam for fire suppression. In this article, to formulate an assessment tool for studying the ideal entrainment ratio and initial flow wetness, a wet steam model has been proposed to enhance our understanding of the condensation and evaporation effects of water droplets from a numerical perspective. The entire steam-ejector system including the nozzle, mixing chamber, throat and diffuser were modeled to study the profiles in axial pressure and temperature across the system, and were compared with self-measured experimental data. In addition, the flow and heat transfer interactions between the fluid mixture and nucleating water droplets were numerically examined by comparing initial conditions with different liquid fractions, as opposed to the ideal gas assumption. With the application of the proposed wet-steam model, the numerical model showed vast improvement in the axial pressure distribution over the ideal gas model. Through numerical conditions, it was found that reducing the wetness of the secondary inlet flow will potentially optimize the system performance with a significant increase of the entrainment ratio from 0.38 to 0.47 (i.e., improvement of around 23%).
Publisher: Informa UK Limited
Date: 02-01-2017
Publisher: IOP Publishing
Date: 12-2019
Abstract: A computational fluid dynamics (CFD) study of the impact characteristics and stagnation formation on a solid target surface by an abrasive waterjet at supersonic velocities is presented to understand the impact process. A CFD model is developed and verified by experimental water and particle velocities and then used to simulate the jet impact process. The trends of the stagnation formation and its effect on the jet flow with respect to the jetting and impacting parameters are ly discussed. It is found that stagnation formation at the impact site increases with an increase in the impact time, nozzle standoff distance and nozzle diameter, while the initial peak velocity at the nozzle exit has little effect on the size of the stagnation zone. It is shown that stagnation markedly changes the water and particle flow direction, so that the particle impact angle is varied and the jet impact area is enlarged. The jet structure may be classified to have a free jet flow region, a jet deflection region with a stagnation zone and a wall jet region. Furthermore, the stagnation affects significantly the waterjet and particle energy transferred to the target surface. The average particle velocity across the jet is reduced by approximately one third due to the d ing effect of the stagnation under the conditions considered in this study.
Publisher: MDPI AG
Date: 18-01-2021
DOI: 10.3390/MOLECULES26020478
Abstract: In recent years, the applications of lithium-ion batteries have emerged promptly owing to its widespread use in portable electronics and electric vehicles. Nevertheless, the safety of the battery systems has always been a global concern for the end-users. The separator is an indispensable part of lithium-ion batteries since it functions as a physical barrier for the electrode as well as an electrolyte reservoir for ionic transport. The properties of separators have direct influences on the performance of lithium-ion batteries, therefore the separators play an important role in the battery safety issue. With the rapid developments of applied materials, there have been extensive efforts to utilize these new materials as battery separators with enhanced electrical, fire, and explosion prevention performances. In this review, we aim to deliver an overview of recent advancements in numerical models on battery separators. Moreover, we summarize the physical properties of separators and benchmark selective key performance indicators. A broad picture of recent simulation studies on separators is given and a brief outlook for the future directions is also proposed.
Publisher: Springer Science and Business Media LLC
Date: 04-03-2011
Publisher: SAGE Publications
Date: 06-2009
DOI: 10.1260/175748209789563946
Abstract: This paper reports on an exemplary study of the performance of Computational Fluid Dynamics (CFD) computer codes for the case study of interfacial flows including surface tension. The finite volume codes of ANSYS, Inc., Fluent and CFX have been evaluated by performing CFD-simulations of collapsing water columns with and without an obstacle within enclosures. In both of these computer codes, the interfaces are treated by the volume of fluid method. The main difference is attributed to the absence of any surface reconstruction algorithms in ANSYS, Inc., CFX. Rather, the so-called “compressive scheme” is applied instead to overcome numerical diffusion and smearing of the interface. ANSYS, Inc., Fluent, however, employs the geometric reconstruction algorithm based on the Piecewise Linear Interface Construction (PLIC) method. The study assesses the simulation results obtained through the two computer codes by comparing against experimental observations and measurements as well as numerical predictions from other CFD codes if available.
Publisher: Elsevier BV
Date: 10-2013
Publisher: ASME International
Date: 03-2005
DOI: 10.1115/1.1857952
Abstract: The capability of using the population balance approach combined with a three-dimensional two-fluid model for predicting subcooled boiling flow is investigated. Experiments were conducted to study the local flow characteristics of subcooled boiling flow and to provide measured local two-phase flow parameters. Calculations were performed using the newly developed population balance boiling model to study the effects of various factors on numerical predication of local two-phase flow parameters in the subcooled boiling regime. Comparison of model predictions against local measurements was made for the radial distribution of the bubble Sauter diameter and void fraction covering a range of different mass and heat fluxes and inlet subcooling temperatures. Additional comparison using recent active nucleation site density models and empirical relationships to determine the local bubble diameter adopted by other researchers was also investigated. Overall, good agreement was achieved between predictions and measurements using the newly formulated population balance approach based on the modified MUSIG (multiple-size-group) model for subcooled boiling and two-fluid model.
Publisher: Informa UK Limited
Date: 05-06-2015
Publisher: MDPI AG
Date: 03-11-2021
DOI: 10.3390/MOLECULES26216662
Abstract: Biomass-derived carbon has been recognised as a green, economic and promising flame retardant (FR) for polymer matrix. In this paper, it is considered that the two-dimensional (2D) structure of carbonised peanut shells (PS) can lead to a physical barrier effect on polymers. The carbonised s le was prepared by the three facile methods, and firstly adopted as flame retardants for epoxy resin. The results of thermal gravimetric analysis (TGA) and cone calorimeter tests indicate that the carbon combined with nano Cobalt provides the most outstanding thermal stability in the current study. With 3 wt.% addition of the FR, both peak heat release rate (pHRR) and peak smoke production rate (PSPR) decrease by 37.9% and 33.3%, correspondingly. The flame retardancy mechanisms of the FR are further explored by XPS and TG-FTIR. The effectiveness of carbonised PS can be mainly attributed to the physical barrier effect derived by PS’s 2D structure and the catalysis effect from Cobalt, which contribute to form a dense char layer.
Publisher: Elsevier BV
Date: 12-2013
Publisher: Wiley
Date: 29-06-2012
DOI: 10.1002/PI.4296
Publisher: Emerald
Date: 27-03-2008
DOI: 10.1108/09615530810846310
Abstract: This study aims to examine both the population balance approach based on the MUltiple SIze Group (MUSIG) model and the average bubble number density transport equation (ABND) model for 3D, low pressure, gas‐liquid, subcooled boiling, vertical flows. The purpose is to assess the ability of both models to predict the radial profile of void fraction, bubble Sauter mean diameter and interfacial area concentration which characterise subcooled boiling. Improvement in the ABND model to simulate gas‐liquid bubbly flows with heat transfer was achieved by combining the condensation expression with the gaseous mass transport equation within the CFD commercial code CFX4.4. Overall, both the ABND model and the MUSIG model provided good results in terms of the above‐mentioned criteria when compared against experimental measurements. However, the ABND model was found to have limitations in predicting high‐subcooled boiling flows due to the lack of bubble size resolution to adequately capture the effect of condensation over a range of bubbles sizes. It is shown that the ABND model provides an economic alternative to the MUSIG model in terms of complexity and computational time, as long as one is aware of the limitations in simulating high‐subcooling flow regimes.
Publisher: MDPI AG
Date: 05-03-2020
Abstract: Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced thermal depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better thermal conductivity and thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.
Publisher: Elsevier BV
Date: 11-2014
Publisher: Elsevier BV
Date: 03-2012
Publisher: Informa UK Limited
Date: 23-06-2015
Publisher: Elsevier BV
Date: 07-2018
Publisher: Elsevier BV
Date: 12-2010
Publisher: Informa UK Limited
Date: 07-08-2020
Publisher: Elsevier BV
Date: 03-2011
Publisher: Begell House
Date: 2013
Publisher: Informa UK Limited
Date: 26-07-2022
Publisher: Informa UK Limited
Date: 05-12-2017
Publisher: Emerald
Date: 02-01-2018
Abstract: Interface distinct two-phase computational fluid dynamics (CFD) simulations require accurate tracking in surface curvature, surface area and volume fraction data to precisely calculate effects such as surface tension, interphase momentum and interphase heat and mass transfer exchanges. To attain a higher level of accuracy in two-phase flow CFD simulations, the intersection marker (ISM) method was developed. The ISM method has cell-by-cell remeshing capability that is volume conservative, maintains surface continuity and is suited for the tracking of interface deformation in transient two-phase flow simulations. Studies of isothermal single bubbles rising in quiescent water were carried out to test the ISM method for two-phase flow simulations. The ISM method is a hybrid Lagrangian–Eulerian front tracking algorithm which can model an arbitrary three-dimensional surface within an array of cubic control volumes. Fortran95 was used to implement the ISM method, which resulted in approximately 25,000+ lines of written code and comments. To demonstrate the feasibility of the ISM algorithm for two-phase flow simulations, the ISM algorithm was coupled with an in-house CFD code, which was modified to simulate two-phase flows using a single fluid formulation. The constitutional equations incorporated terms of variable density and viscosity. In addition, body force source terms were included in the momentum equation to account for surface tension and buoyancy effects. The performance of two-phase flow simulations was benchmarked against experimental data for four air/water bubbles with 1, 2.5, 5 and 10 mm of diameter rising in quiescent fluid. A variety of bubble sizes were tested to demonstrate the accuracy of the ISM interface tracking method. The results attained were in close agreement with experimental observations. The results obtained show that the ISM method is a viable means for interface tracking of two-phase flow CFD simulations. Other applications of the ISM method include simulations of solid–fluid interaction and other immersed boundary flow problems. The ISM method is a novel approach to front tracking, and the results shown are original in content.
Publisher: Elsevier BV
Date: 10-2006
Publisher: Elsevier BV
Date: 12-2012
Publisher: American Society of Mechanical Engineers
Date: 08-07-2012
Abstract: A three-dimensional computational model has been developed to investigate the cooling effect on the microchip of synthetic jet interacting with a cross-flow in a micro-channel. The conjugate problem is solved by determining the temperature distributions in a heated solid and the fluid flowing in the micro-channel which cools it, thereby simulating the application to a microchip. A parametric study was performed on a fixed geometry by using 1 MWm−2 heat flux at the surface of the silicon wafer to investigate the effect of frequency of the jet at a constant Reynolds number, that is the litude is reduced in proportion to the increase in frequency. The hot region in the silicon wafer resulting from the use fluid flowing undisturbed in a micro-channel, are removed when the synthetic jet is switched on thereby significantly lowering the maximum temperature in the wafer. Contrary to the two-dimensional case, there is little difference in the cooling performance when the jet was driven at different frequencies in three-dimensional configuration. This is illustrated by the fact in the end of the simulations at a jet Reynolds number of 40, the maximum temperature in the substrate was 0.5 K lower at 1120 Hz than at 560 Hz and 1 K lower than at 280 Hz.
Publisher: SPIE
Date: 09-08-2013
DOI: 10.1117/12.2028606
Publisher: Begellhouse
Date: 2012
Publisher: Elsevier BV
Date: 2012
Publisher: SAGE Publications
Date: 03-2013
Abstract: The VOF (Volume of Fluids) and CLSVOF (Coupled Level Set and VOF) methods are both methodologies in capturing the interface of two phase fluids. Despite some comparison on the rising velocity and interface capturing for certain simple cases of bubbles at certain times of the simulation, no full comparison of the interface capturing for cases of breakups and coalescence along with the stage by stage interface comparison has been completed. In this paper, the shape and deformation of buoyancy driven spherical bubble rising in a 2D channel is numerically investigated. The VOF and CLSVOF models have been used in the numerical simulation and the results were compared both qualitatively and numerically for both models. This specific bubble size and case was chosen since it involves breaking up, coalescence and deformation which is essential in examining the ability of accurate interface capturing of different methodologies. The results show the effectiveness and faster mesh convergence of the CLSVOF method however higher computational time is required for this method. The results show that while the VOF method required a finer mesh to capture the bubble accurately, the CLSVOF has effect on the shape of the bubble, and significant effects on the velocity field and wake pressure.
Publisher: SAGE Publications
Date: 20-09-2018
Abstract: In this article, a generic framework was proposed to effectively characterise the pyrolysis kinetics of any household furniture materials. To examine the validity of this method, two wooden polymeric s les, (1) furniture plywood and (2) particle board, were experimented through thermogravimetric and differential thermal analyses, as well as cone calorimetry. The framework comprises of three major parameterisation procedures including (1) using the Kissinger method for the initial approximation, (2) modification of modelling constants and (3) optimisation by comparisons with the experimental results. The finalised pyrolysis kinetics was numerically investigated through computational fluid dynamics simulation of the cone calorimeter. Numerical predictions were validated against the experimental data for three different cone radiation intensities. Good agreement was achieved between the computational and experimental results in terms of heat release rate, ignition time and burn duration. The proposed framework was capable of establishing quality pyrolysis kinetics that fully replicates the complex thermal decomposition of solid combustible materials.
Publisher: Springer Singapore
Date: 04-09-2020
Publisher: MDPI AG
Date: 12-11-2019
DOI: 10.3390/APP9224842
Abstract: A paradigm shift towards the utilization of carbon-neutral and low emission fuels is necessary in the internal combustion engine industry to fulfil the carbon emission goals and future legislation requirements in many countries. Hydrogen as an energy carrier and main fuel is a promising option due to its carbon-free content, wide flammability limits and fast flame speeds. For spark-ignited internal combustion engines, utilizing hydrogen direct injection has been proven to achieve high engine power output and efficiency with low emissions. This review provides an overview of the current development and understanding of hydrogen use in internal combustion engines that are usually spark ignited, under various engine operation modes and strategies. This paper then proceeds to outline the gaps in current knowledge, along with better potential strategies and technologies that could be adopted for hydrogen direct injection in the context of compression-ignition engine applications—topics that have not yet been extensively explored to date with hydrogen but have shown advantages with compressed natural gas.
Publisher: ASME International
Date: 15-03-2017
DOI: 10.1115/1.4035805
Abstract: Modeling subcooled boiling flows in vertical channels has relied heavily on the utilization of empirical correlations for the active nucleation site density, bubble departure diameter, and bubble departure frequency. Following the development and application of mechanistic modeling at low pressures, the capability of the model to resolve flow conditions at elevated pressure up to 10 bar is thoroughly assessed and compared with selected empirical models. Predictions of the mechanistic and selected empirical models are validated against two experimental data at low to elevated pressures. The results demonstrate that the mechanistic model is capable of predicting the heat and mass transfer processes. In spite of some drawbacks of the currently adopted force balance model, the results still point to the great potential of the mechanistic model to predict a wide range of flow conditions in subcooled boiling flows.
Publisher: Elsevier BV
Date: 07-2018
Publisher: Elsevier BV
Date: 02-2004
Publisher: MDPI AG
Date: 17-02-2021
DOI: 10.3390/PR9020368
Abstract: Gold nanoparticles (GNP) aided hyperthermia has demonstrated promising results in the treatment of cancer. However, most existing investigations focus only on the extinction spectra of GNP solutions, few reported the actual heat generation capability of these solutions to estimate their real potential in in-situ hyperthermia treatment. In this study, the impact of GNP clustering on the optical properties and heating capability of GNP aggregates in acidic solutions have been investigated. It was found that localized heat generation could be significantly enhanced (to up to 60.0 °C) when acidic solutions were illuminated by a near infrared light source at 1.7 W/cm2. In addition, infrared thermography imaging can only detect the surface temperature during thermal treatment, leaving the localized temperature distribution inside the tissues unknown. To overcome this limitation, in this study, the absorbed energy during NIR irradiation in GNP solutions was obtained computationally by coupling the P1 approximation with the DDA calculation to predict the localized temperature change in the solutions. It was demonstrated that due to the accumulation and dissipation of heat, some local areas showed higher temperature increase with the hot spots being connected and merged over time.
Publisher: MDPI AG
Date: 19-10-2019
DOI: 10.3390/APP9204435
Abstract: In general, engine fuel combustion generates 30% waste heat, which is disposed to the environment. The use of the steam ejector refrigeration to recycle the waste heat and transfer them to useful energy source could be an environmentally friendly solution to such an issue. The steam ejector is the main component of the ejector refrigeration system, which can operate at a low-temperature range. In this article, the internal shock wave structure of the ejector is comprehensively studied through the computation fluid dynamics (CFD) approach. The shock wave structure can be sub ided into two regions: firstly the pseudo-shock region consisting of shock train and co-velocity region secondly the oblique-shock region composed of a single normal shock and a series of oblique shocks. The effect of the shock wave structure on both pumping performance and the critical back pressure were investigated. Numerical predictions indicated that the entrainment ratio is enhanced under two conditions including (i) a longer pseudo-shock region and (ii) when the normal shock wave occurs near the outlet. Furthermore, the system is stabilized as the back pressure and its disturbance is reduced. A critical range of the primary fluid pressure is investigated such that the pumping is effectively optimized.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 08-2004
Publisher: Elsevier
Date: 2014
Publisher: MDPI AG
Date: 08-10-2019
DOI: 10.3390/APP9194189
Abstract: Magnetorheological (MR) fluid is a smart material fabricated by mixing magnetic-responsive particles with non-magnetic-responsive carrier fluids. MR fluid d ers are able to provide rapid and reversible changes to their d ing coefficient. To optimize the efficiency and effectiveness of such devices, a computational model is developed and presented where the flow field is simulated using the computational fluid dynamics approach, coupled with the magnetohydrodynamics model. Three different inlet pressure profiles were designed to replicate real loading conditions are examined, namely a constant pressure, a sinusoidal pressure profile, and a pressure profile mimicking the 1994 Northbridge earthquake. When the MR fluid d er was in its off-state, a linear pressure drop between the inlet and the outlet was observed. When a uniform perpendicular external magnetic field was applied to the annular orifice of the MR d er, a significantly larger pressure drop was observed across the annular orifice for all three inlet pressure profiles. It was shown that the fluid velocity within the magnetized annular orifice decreased proportionally with respect to the strength of the applied magnetic field until saturation was reached. Therefore, it was clearly demonstrated that the present model was capable of accurately capturing the d ing characteristics of MR fluid d ers.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 2016
Publisher: SAGE Publications
Date: 03-2012
Abstract: Numerical simulation of flow through a realistic bifurcated carotid artery geometry with a stenosis has been conducted for comparison to experimental measurements. The behaviour of simplified therapeutic nanoparticles in relatively low concentration was observed using a discrete particle approach. The role of size (diameters from 500 nm to 50 nm) in determining particle residence time and the potential for both desirable and undesirable wall interactions was investigated. It was found that mean particle residence time reduced with decreasing particle diameter, and the percentage of particles experiencing one or more wall interactions increased simultaneously. Further simulations were conducted on a scaled-down version of the geometry which approximated the size and flow conditions of an arteriole with capillary branches, and in this instance the mean residence time increased with decreasing particle diameter, owing largely to the greater influence of Brownian motion. 33% of all 50 nm particles were involved in wall interactions, indicating that smaller particles would have a greater ability to target, for instance, cancerous tumours in such regions.
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 08-2014
Publisher: SAGE Publications
Date: 27-08-2018
Abstract: In this paper, the mechanistic wall heat partitioning approach was used to capture the complex heat and mass transfer in sub-cooled boiling flows. In order to accommodate the changes of local variables to be relevant to the physical properties of sub-cooled fluids, the Wet-Steam (IAPWS-IF97) is used as the working fluid. Currently, the approach is evaluated based on the bubble sliding along the wall before lifting-off, which is usually found in the flow boiling situations. In the simulation, the closure mechanistic models, including the fractal analysis, the force balance and the mechanistic frequency, were coupled with the Eulerian–Eulerian two-fluid framework, while the Shear Stress Transport model was used as a turbulent modelling closure. The Multiple Size Group model was introduced to handle the bubble interactions and predict the bubble size distribution. Moreover, the effect of adopting the sub-cooled liquid properties into the modelling was investigated and compared with the experiments over a wide range of flow conditions. Specifically, the predicted void fraction and the sub-cooling temperature near the heated wall were precisely compared with the cases of using the constant-property liquid. Overall, the satisfactory agreements were found between the experiments and the predictions of the liquid temperature, void fraction, interfacial area concentration, Sauter mean diameter and bubble and liquid velocities with the exception of the case of high heat and mass fluxes. To enhance the current prediction accuracy for a situation of having a high superheating temperature, more bubble interactions on the boiling wall, such as merging of the bubbles while sliding, need to be considered. Furthermore, to assess the model capability, this mechanistic approach will be introduced to elucidate the sub-cooled boiling flow in situations of using different fluids in the near future.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5LC00633C
Abstract: The article describes flow-induced stress on adherent cells in microfluidics devices in light of ongoing discoveries in mechanobiology.
Publisher: MDPI AG
Date: 04-11-2022
Abstract: With the increasing demand for energy capacity and power density in battery systems, the thermal safety of lithium-ion batteries has become a major challenge for the upcoming decade. The heat transfer during the battery thermal runaway provides insight into thermal propagation. A better understanding of the heat exchange process improves a safer design and enhances battery thermal management performance. This work proposes a three-dimensional thermal model for the battery pack simulation by applying an in-house model to study the internal battery thermal propagation effect under the computational fluid dynamics (CFD) simulation framework. The simulation results were validated with the experimental data. The detailed temperature distribution and heat transfer behaviour were simulated and analyzed. The thermal behaviour and cooling performance were compared by changing the abnormal heat generation locations inside the battery pack. The results indicated that various abnormal heat locations disperse heat to the surrounding coolant and other cells. According to the current battery pack setups, the maximum temperature of Row 2 cases can be increased by 2.93%, and the temperature difference was also increased. Overall, a new analytical approach has been demonstrated to investigate several stipulating battery thermal propagation scenarios for enhancing battery thermal performances.
Publisher: Wiley
Date: 21-05-2015
DOI: 10.1002/CJCE.22196
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.JHAZMAT.2019.04.026
Abstract: Thermoplastic polyurethane (TPU) has broad applications as lightweight materials due to its multiple advantages and unique properties. Nevertheless, toxicity emission under fire conditions remains a major concern, particularly in building fire scenarios. To circumvent the problem, it is imperative that an effective flame retardant is sought to suppress the flame and release of combustion/smoke products whilst maintaining the favorable material properties of TPU. In the current work, a simple method is proposed for the preparation and utilization of cetyltrimethyl ammonium bromide (CTAB) and tetrabutyl phosphine chloride (TBPC) modified Ti
Publisher: Elsevier BV
Date: 2012
Publisher: Elsevier BV
Date: 03-2012
Publisher: ASMEDC
Date: 2010
DOI: 10.1115/IHTC14-22524
Abstract: An in-house computer code is developed and applied to investigate the effect of a synthetic jet on heat transfer rates in forced convection of water in silicon micro-channels etched in the rear side of the silicon substrate. To account for the deflection of the membrane located at the bottom of the actuator cavity, a moving mesh technique to solve the flow and heat transfer is purposefully adopted. The governing equations are transformed into the curvilinear coordinate system in which the grid velocities evaluated are then fed into the computation of the flow in the cavity domain thus allowing the conservation equations of mass, momentum and energy to be solved within the stationary computational domain. The fully three-dimensional model considers the SIMPLE method to link the pressure and velocity. A heat flux of 1 MW/m2 is applied at the surface of the top of the silicon wafer and the resulting complex, conjugate heat transfer through the silicon substrate is included. The hydrodynamics feature of the flow is validated against existing experimental results and verified against numerical results from commercial package ANSYS CFX 11.0. Good agreement has been achieved. To track the development of the flow and heat transfer when the actuator is switched on, numerical results of 20 full cycles of the actuator are simulated. When the actuator is switched on, noticeable temperature drop is observed at all points in the substrate from those which existed when there has been a steady water flow in the channel. At the end of 20th cycle of actuation, the maximum temperature in the wafer has reduced by 5.4 K in comparison with the steady flow values. In comparison with the two-dimensional study which account for 17K reduction, it indicates that synthetic jet has only smaller beneficial cooling and has been over-estimated in the previous two-dimensional study.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Informa UK Limited
Date: 02-05-2016
Publisher: Begell House
Date: 2013
Publisher: Informa UK Limited
Date: 04-2011
Publisher: SAGE Publications
Date: 09-2012
Publisher: Elsevier BV
Date: 10-2017
Publisher: Springer Science and Business Media LLC
Date: 03-2004
Publisher: Informa UK Limited
Date: 04-05-2017
Publisher: SAGE Publications
Date: 22-11-2016
Abstract: The main focus in the analysis of pool or flow boiling in saturated or subcooled conditions is the basic understanding of the phase change process through the heat transfer and wall heat flux partitioning at the heated wall and the two-phase bubble behaviours in the bulk liquid as they migrate away from the heated wall. This paper reviews the work in this rapid developing area with special reference to modelling nucleate boiling of cryogenic liquids in the context of computational fluid dynamics and associated theoretical developments. The partitioning of the wall heat flux at the heated wall into three components – single-phase convection, transient conduction and evaporation – remains the most popular mechanistic approach in predicting the heat transfer process during boiling. Nevertheless, the respective wall heat flux components generally require the determination of the active nucleation site density, bubble departure diameter and nucleation frequency, which are crucial to the proper prediction of the heat transfer process. Numerous empirical correlations presented in this paper have been developed to ascertain these three important parameters with some degree of success. Albeit the simplicity of empirical correlations, they remain applicable to only a narrow range of flow conditions. In order to extend the wall heat flux partitioning approach to a wider range of flow conditions, the fractal model proposed for the active nucleation site density, force balance model for bubble departing from the cavity and bubble lifting off from the heated wall and evaluation of nucleation frequency based on fundamental theory depict the many enhancements that can improve the mechanistic model predictions. The macroscopic consideration of the two-phase boiling in the bulk liquid via the two-fluid model represents the most effective continuum approach in predicting the volume fraction and velocity distributions of each phase. Nevertheless, the interfacial mass, momentum and energy exchange terms that appear in the transport equations generally require the determination of the Sauter mean diameter or interfacial area concentration, which strongly governs the fluid flow and heat transfer in the bulk liquid. In order to accommodate the dynamically changing bubble sizes that are prevalent in the bulk liquid, the mechanistic approach based on the population balance model allows the appropriate prediction of local distributions of Sauter mean diameter or interfacial area concentration, which in turn can improve the predictions of the interfacial mass, momentum and energy exchanges that occur across the interface between the phases. Need for further developments are discussed.
Publisher: Springer Science and Business Media LLC
Date: 06-2022
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 09-2011
Publisher: Elsevier
Date: 2008
Publisher: Elsevier BV
Date: 2011
Publisher: Emerald
Date: 03-2002
DOI: 10.1108/09615530210418320
Abstract: This paper presents a comparison of numerical predictions employing a Computational Fluid Dynamics fire model against a series of turbulent buoyant fire experiments recently carried out in a two‐room compartment structure by Nielsen and Fleischmann at the University of Canterbuty, New Zealand. The model incorporates turbulence, combustion, soot generation and radiation due to a fire. An evaluation of the various approaches—volumetric heat source approach or a more sophisticated handling the fire through a combustion model—is carried out. The effect of radiation due to combustion products and soot is also investigated. The model considering combustion with radiation contribution by both the combustion products and soot provides the best agreement between the predicted results and measured data. The presence of soot is seen to significantly augment the global radiation process within the two‐compartment enclosure.
Publisher: American Chemical Society (ACS)
Date: 06-11-2018
Publisher: Informa UK Limited
Date: 10-02-2016
DOI: 10.1080/10255842.2016.1145211
Abstract: Three-dimensional numerical calculations of mild and moderate stenosed blood vessels have been performed. Large eddy simulation through a dynamic subgrid scale Smagorinsky model is applied to model the transitional and turbulent pulsatile flow. For the compliant stenosed model, fluid-structure interaction is realized through a two-way coupling between the fluid flow and the deforming vessel through the change in the external diameter due to the increment of circumferential pressure via a novel moving boundary approach. Model predictions compare very well against measured and numerical data for the centerline velocities, thickness of the flow separation zones and radial wall displacements.
Publisher: MDPI AG
Date: 13-10-2022
DOI: 10.3390/FIRE5050165
Abstract: In this article, a collective database from validated numerical simulation has been established to study the suppression effects of water-based suppression systems under a single-compartment fire scenario at various suppression configurations and fire locations. Five fuel locations along the axis between the centre and corner of the room were configurated to dynamically analyse how the horizontal distance between the nozzle and fuel pan affects the heat release rate (HRR), temperature cooling phenomena at different heights and also the velocity profile. Throughout the fuel pan relocations, the water-mist system has achieved an average suppression time of 25 s for all the locations, it was found that the water mist system can effectively control the fire under 200 °C that is distanced over 2 m spanwise displacement from the nozzle against the fire, while the sprinkler has exhibited an excellent fuel surface cooling effect due to large momentum and heat capacity within the coverage area with an average suppression time of 50 s. The results of this study have further explored the spray coverage and droplet penetrability of different suppression systems at different locations corresponding to the fire source, and the quantitative assessment of fuel locations could also contribute to the future development of performance-based fire safety designs.
Publisher: Springer Science and Business Media LLC
Date: 07-2019
Publisher: Informa UK Limited
Date: 26-12-2018
Publisher: Elsevier BV
Date: 10-2017
Publisher: Springer Science and Business Media LLC
Date: 18-10-2016
DOI: 10.1038/SREP35618
Abstract: Regulation of tissue development and repair depends on communication between neighbouring cells. Recent advances in cell micro-contact printing and microfluidics have facilitated the in-vitro study of homotypic and heterotypic cell-cell interaction. Nonetheless, these techniques are still complicated to perform and as a result, are seldom used by biologists. We report here development of a temporarily sealed microfluidic st ing device which utilizes a novel valve design for patterning two adherent cell lines with well-defined interlacing configurations to study cell-cell interactions. We demonstrate post-st ing cell viability of %, the st ing of multiple adherent cell types, and the ability to control the seeded cell density. We also show viability, proliferation and migration of cultured cells, enabling analysis of co-culture boundary conditions on cell fate. We also developed an in-vitro model of endothelial and cardiac stem cell interactions, which are thought to regulate coronary repair after myocardial injury. The st is fabricated using microfabrication techniques, is operated with a lab pipettor and uses very low reagent volumes of 20 μl with cell injection efficiency of %. This easy-to-use device provides a general strategy for micro-patterning of multiple cell types and will be important for studying cell-cell interactions in a multitude of applications.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Springer Science and Business Media LLC
Date: 05-2016
Publisher: Springer Science and Business Media LLC
Date: 31-05-2008
Publisher: Informa UK Limited
Date: 04-2005
Publisher: MDPI AG
Date: 08-03-2019
DOI: 10.3390/EN12050910
Abstract: In this article, the evolution of in-flame soot species in a slow speed, buoyancy-driven diffusion flame is thoroughly studied with the implementation of the population balance approach in association with computational fluid dynamics (CFD) techniques. This model incorporates interactive fire phenomena, including combustion, radiation, turbulent mixing, and all key chemical and physical formation and destruction processes, such as particle inception, surface growth, oxidation, and aggregation. The in-house length-based Direct Quadrature Method of Moments (DQMOM) soot model is fully coupled with all essential fire sub-modelling components and it is specifically constructed for low-speed flames. Additionally, to better describe the combustion process of the parental fuel, ethylene, the strained laminar flamelet model, which considers detailed chemical reaction mechanisms, is adopted. Numerical simulation is validated against a self-conducted co-flow slot burner experimental measurement. A comprehensive assessment of the effect of adopting different nucleation laws, oxidation laws, and various fractal dimension and diffusivity values is performed. The results suggest the model employing Moss law of nucleation, modified NSC law of oxidation, and adopting a fractal dimension value of 2.0 and Schmidt number of 0.9 yields the simulation result that best agreed with experimental data.
Publisher: Elsevier BV
Date: 11-2019
Publisher: Informa UK Limited
Date: 13-12-2008
Publisher: Wiley
Date: 28-08-2012
DOI: 10.1002/APP.38399
Publisher: American Chemical Society (ACS)
Date: 03-07-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2017
Publisher: Springer Science and Business Media LLC
Date: 07-11-2017
Publisher: Elsevier BV
Date: 06-2012
Publisher: Begellhouse
Date: 2012
Publisher: SAGE Publications
Date: 06-2009
DOI: 10.1260/175748209789563928
Abstract: In this article, we present a review of the state-of-the-art population balance modelling techniques that have been adopted to describe the phenomenological nature of isothermal bubbly flows. The main focus of the review can be broadly classified into three categories: (i) Numerical approaches or solution algorithms of the PBE (ii) Applications of the PBE in practical gas-liquid multiphase problems and (iii) Possible aspects of the future development in population balance modelling. For the first category, details of solution algorithms based on both method of moment (MOM) and discrete class method (CM) that have been proposed in the literature are provided. Advantages and drawbacks of both approaches are also discussed from the theoretical and practical viewpoints. For the second category, applications of existing population balance models in practical multiphase problems that have been proposed in the literature are summarized. Selected existing mathematical closures for modelling the “birth” and “death” rate of bubbles in gas-liquid bubbly flows are introduced. Particular attention is devoted to assess the capability of some selected models in predicting bubbly flow conditions through detail validation studies against experimental data. These studies demonstrate that good agreement can be achieved by the present model by comparing the predicted results against measured data with regards to the radial distribution of void fraction and sauter mean bubble diameter. Finally, weaknesses and limitations of the existing models are revealed are suggestions for further development are discussed. Emerging topics for future population balance studies are provided as to complete the aspect of population balance modelling.
Publisher: Elsevier BV
Date: 02-2013
Publisher: IEEE
Date: 04-2019
Publisher: Elsevier BV
Date: 07-2008
Publisher: Elsevier BV
Date: 02-2003
Publisher: Elsevier BV
Date: 12-2011
Publisher: SAGE Publications
Date: 03-2012
Abstract: Two-fluid modeling approach is considered as one of the most practical and accurate macroscopic formulation of handling bubbly flow systems. Nevertheless, in order to rigorously account for bubble-bubble interactions, the population balance equation (PBE) must be solved alongside with the continuity and momentum balance equations. Class method typified by the MUltiple SIze Group (MUSIG) model appears to be one of the most direct methods to solve the PBE using a finite series of discrete classes. In this paper, an alternative approach based on the direct quadrature method of moments (DQMOM) is investigated. In contrast to MUSIG model which requires a large number of classes to resolve the bubble distribution, the main advantage of DQMOM is that the number of moments to be solved is generally very small. Validation and assessment of the two population balance models are carried out against measurements of vertical bubbly flows for a range of flow conditions. Based on the present study, preliminary computed results have been found to compare very well against the experimental data as well as the numerical results predicted through the MUSIG model.
Publisher: Elsevier BV
Date: 11-2005
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 06-2016
Publisher: MDPI AG
Date: 04-01-2022
DOI: 10.3390/MOLECULES27010292
Abstract: Building polymers implemented into building panels and exterior façades have been determined as the major contributor to severe fire incidents, including the 2017 Grenfell Tower fire incident. To gain a deeper understanding of the pyrolysis process of these polymer composites, this work proposes a multi-scale modelling framework comprising of applying the kinetics parameters and detailed pyrolysis gas volatiles (parent combustion fuel and key precursor species) extracted from Molecular Dynamics models to a macro-scale Computational Fluid Dynamics fire model. The modelling framework was tested for pure and flame-retardant polyethylene systems. Based on the modelling results, the chemical distribution of the fully decomposed chemical compounds was realised for the selected polymers. Subsequently, the identified gas volatiles from solid to gas phases were applied as the parent fuel in the detailed chemical kinetics combustion model for enhanced predictions of toxic gas, charring, and smoke particulate predictions. The results demonstrate the potential application of the developed model in the simulation of different polymer materials without substantial prior knowledge of the thermal degradation properties from costly experiments.
Publisher: Elsevier BV
Date: 05-2016
Publisher: MDPI AG
Date: 17-01-2018
DOI: 10.20944/PREPRINTS201801.0161.V1
Abstract: High-performance poly(1,4-butylene terephthalate (PBT) nanocomposites have been developed via the consideration of phosphorus-containing agents and amino-carbon nanotube (A-CNT). One-pot functionalization method has been adopted to prepare functionalized CNTs via the reaction between A-CNT and different oxidation state phosphorus-containing agents, including chlorodiphenylphosphine (DPP-Cl), diphenylphosphinic chloride (DPP(O)-Cl), and diphenyl phosphoryl chloride (DPP(O3)-Cl). These functionalized CNTs, DPP(Ox)-A-CNTs (x = 0, 1, 3), were respectively mixed with PBT to obtain the CNTs-based polymer nanocomposites through a melt blending method. SEM observations demonstrated that DPP(Ox)-A-CNT nano-additives were homogeneously distributed within PBT matrix compared to A-CNT. The incorporation of DPP(Ox)-A-CNT improved the thermal stability of PBT. Moreover, PBT/DPP(O3)-A-CNT showed the highest crystallization temperature and tensile strength, due to the superior dispersion and interfacial interactions between DPP(O3)-A-CNT and PBT. PBT/DPP(O)-A-CNT exhibited the best flame retardancy resulting from the excellent carbonization effect. The radicals generated from decomposed polymer were effectively trapped by DPP(O)-A-CNT, leading to the reduction of heat release rate, smoke production rate, carbon dioxide and carbon monoxide release during cone calorimeter tests.
Publisher: MDPI AG
Date: 15-05-2020
DOI: 10.3390/APP10103428
Abstract: The fundamental flow structure and temperature distribution of small-scale fire whirls, including tangential and axial velocities, temperature variation, and air entrainment in the lower boundary layer, were successfully captured using a generic fire field model with large eddy simulation (LES) turbulence closure. Numerical predictions were validated thoroughly against two small-scale experimental measurements, where detailed temperature and velocity distributions were recorded. Good agreement between numerical and experimental results was achieved. Normalization was also performed to compare the numerical predictions with the empirical correlations by Lei et al. (2015) developed from medium-scale fire whirl measurements. The transient development stages of small-scale fire whirls and the impact of air entrainment on the stability of the fire whirls were also investigated based on the validated numerical results. The numerical validations showed the potential of the current LES fire field model in capturing the dynamic behaviour of the fire whirl plume and performing a quantitative analysis on its onset criteria and combustion dynamics in future.
Publisher: MDPI AG
Date: 20-09-2022
DOI: 10.3390/FIRE5050140
Abstract: Demand for underground railways has rapidly increased due to accelerated urbanisation and population growth. This has elevated the importance of tunnel designs with adequate fire safety and protection measures. However, due to intricate modern rail tunnel designs, prescriptive codes are often difficult to implement and lead to over-conservative design. In this study, the current state of tunnel fire analysis was reviewed with a focus on Australia. A large-eddy simulation (LES)-based fire model was applied to investigate the temperature and smoke dispersion from a 2 MW metro tunnel fire case scenario to the cross-passage. A total of 28 cases with various cross-passage ventilation settings were examined, including longitudinal tunnel velocity, cross-passage velocity, train location relative to the cross-passage and fire location. The modelling showed that a 0.84 m/s critical velocity was sufficient for smoke control in the cross-passage. Furthermore, two empirical methods for cross-passage critical velocity were performed, which showed utilisation of the Froude number produced a less conservative critical velocity (0.610 m/s) compared to the dimensionless method (0.734 m/s). Nevertheless, both numerical and empirical results were significantly lower than the standard 1.0 m/s minimum flow rate for smoke control (AS1668.1). The results provide preliminary evidence towards the need for revision of current tunnel fire standards and response protocols.
Publisher: Elsevier BV
Date: 09-2016
Publisher: Wiley
Date: 25-10-2016
DOI: 10.1002/FLD.4182
Publisher: Elsevier BV
Date: 2013
Publisher: MDPI AG
Date: 24-09-2019
DOI: 10.3390/APP9193989
Abstract: This paper numerically examines the characterisation of fire whirl formulated under various entrainment conditions in an enclosed configuration. The numerical framework, integrating large eddy simulation and detailed chemistry, is constructed to assess the whirling flame behaviours. The proposed model constraints the convoluted coupling effects, e.g., the interrelation between combustion, flow dynamics and radiative feedback, thus focuses on assessing the impact on flame structure and flow behaviour solely attribute to the eddy-generation mechanisms. The baseline model is validated well against the experimental data. The data of the comparison case, with the introduction of additional flow channelling slit, is subsequently generated for comparison. The result suggests that, with the intensified circulation, the generated fire whirl increased by 9.42 % in peak flame temperature, 84.38 % in visible flame height, 6.81 % in axial velocity, and 46.14 % in velocity dominant region. The fire whirl core radius of the comparison case was well constrained within all monitored heights, whereas that of the baseline tended to disperse at 0.5 m height-above-burner. This study demonstrates that lified eddy generation via the additional flow channelling slit enhances the mixing of all reactant species and intensifies the combustion process, resulting in an elongated and converging whirling core of the reacting flow.
Publisher: SAGE Publications
Date: 03-2015
Abstract: Magnetic drug targeting is continuing to draw attention as a potential technique for cancer and tumour treatment. This paper focuses on the development of computational fluid dynamic models for magnetic drug targeting. Magnetic particle capture has been simulated in a 90 o coronary artery bend of circular tube for a range of different particle sizes. The magnetic field is produced by a current carrying wire. It has been found that increasing the sizes of magnetic particles increases the capture of particles. Extensions are made on the model to include the effects of non-Newtonian fluid and the pulsating nature of blood flow. These extensions improved the basic model by simulating a more physiologically accurate application of magnetic drug targeting. A reduction of the particle capture efficiency is experienced based on this physiologically accurate model. Time of injection over the flow cycle of the pulsating nature of blood flow greatly influences the particle capture efficiency.
Publisher: AIP
Date: 2012
DOI: 10.1063/1.4756076
Publisher: Elsevier BV
Date: 12-2009
Publisher: Elsevier BV
Date: 11-2016
Publisher: SAGE Publications
Date: 2014
DOI: 10.1155/2014/792050
Publisher: MDPI AG
Date: 18-09-2022
DOI: 10.3390/FIRE5050139
Abstract: Building polymers are highly flammable and produce a vast amount of toxic chemical compounds in the event of a fire which can lead to potential incapacitation and death. To gain an in-depth understanding of this issue, smoke toxicity and thermal characteristics of seven commonly used building polymers were analysed through a systematic fire performance evaluation system using a Thermogravimetric Analyzer and a Cone Calorimeter coupled with an FTIR arrangement. Four Fractional Effective Dose (FED) expressions were compared to assess the smoke toxicity of the fire effluents based on different assumptions. It was found that FEDN2, calculated using Purser’s equation, reported the highest values of FED with the following order of potential smoke toxicity at 50 kW/m2 radiative heat flux: LDPU HDPU PE HDEPS XPS EVA LDEPS. Furthermore, fire performance evaluation of the polymers was carried out by considering three key fire risk parameters, i.e., flashover propensity, total heat released, and toxic hazard. At 50 kW/m2 radiative heat flux, HDPU exhibited 11.7 times flashover propensity compared to the least flammable polymer (HDEPS), EVA exhibited 5 times total heat release compared to the polymer with the lowest total heat release (LDEPS) and, LDPU exhibited 6.7 potential times toxic hazard compared to the least toxic polymer (EVA).
Publisher: American Chemical Society (ACS)
Date: 09-07-2018
Publisher: Elsevier BV
Date: 09-2012
Publisher: Informa UK Limited
Date: 07-2004
Publisher: MDPI AG
Date: 03-06-2019
Abstract: Fabricating high-performance MXene-based polymer nanocomposites is a huge challenge because of the poor dispersion and interfacial interaction of MXene nanosheets in the polymer matrix. To address the issue, MXene nanosheets were successfully exfoliated and subsequently modified by long-chain cationic agents with different chain lengths, i.e., decyltrimethylammonium bromide (DTAB), octadecyltrimethylammonium bromide (OTAB), and dihexadecyldimethylammonium bromide (DDAB). With the long-chain groups on their surface, modified Ti3C2 (MXene) nanosheets were well dispersed in N,N-dimethylformamide (DMF), resulting in the formation of uniform dispersion and strong interfacial adhesion within a polystyrene (PS) matrix. The thermal stability properties of cationic modified Ti3C2/PS nanocomposites were improved considerably with the temperatures at 5% weight loss increasing by 20 °C for DTAB-Ti3C2/PS, 25 °C for OTAB-Ti3C2/PS and 23 °C for DDAB-Ti3C2/PS, respectively. The modified MXene nanosheets also enhanced the flame-retardant properties of PS. Compared to neat PS, the peak heat release rate (PHRR) was reduced by approximately 26.4%, 21.5% and 20.8% for PS/OTAB-Ti3C2, PS/DDAB-Ti3C2 and PS/DTAB-Ti3C2, respectively. Significant reductions in CO and CO2 productions were also obtained in the cone calorimeter test and generally lower pyrolysis volatile products were recorded by PS/OTAB-Ti3C2 compared to pristine PS. These property enhancements of PS nanocomposites are attributed to the superior dispersion, catalytic and barrier effects of Ti3C2 nanosheets.
Publisher: Elsevier
Date: 2010
Publisher: Elsevier BV
Date: 12-2008
Publisher: Elsevier BV
Date: 10-2006
Publisher: MDPI AG
Date: 2020
DOI: 10.3390/APP10010318
Abstract: A numerical study of the fire whirl formation under symmetrical and asymmetrical entraining configuration is presented. This work aims to assess the effect of eddy-generation configuration on the evolution of the intriguing phenomenon coupled with both flow dynamics and combustion. The numerical framework implements large-eddy simulation, detailed chemistry to capture the sophisticated turbulence-chemistry interaction under reasonable computational cost. It also adopts liquid-based clean fuel with fixed injection rate and uniformed discretisation scheme to eliminate potential interference introduced by various aspects of uncertainties. The result reveals that the nascent fire whirl formulates significantly rapidly under the symmetrical two-slit configuration, with extended flame height and constrained vortex structure, compared with the asymmetrical baseline. However, its revolution orbit gradually erges from domain centreline and eventually stabilises with a large radius of rotation, whereas the revolution pattern of that from the baseline case is relatively unchanged from the inception of nascent fire whirl. Through the analysis, the observed difference in evaluation pathway could be explained using the concept of circular motion with constant centripetal force. This methodology showcases its feasibility to reveal and visualise the fundamental insight and facilitate profound understanding of the flaming behaviour to benefit both research and industrial sectors.
Publisher: Elsevier BV
Date: 07-2004
Publisher: Hindawi Limited
Date: 2011
DOI: 10.1155/2011/358940
Abstract: A synthetic jet results from periodic oscillations of a membrane in a cavity. Jet is formed when fluid is alternately sucked into and ejected from a small cavity by the motion of membrane bounding the cavity. A novel moving mesh algorithm to simulate the formation of jet is presented. The governing equations are transformed into the curvilinear coordinate system in which the grid velocities evaluated are then fed into the computation of the flow in the cavity domain thus allowing the conservation equations of mass and momentum to be solved within the stationary computational domain. Numerical solution generated using this moving mesh approach is compared with an experimental result measuring the instantaneous velocity fields obtained by μPIV measurements in the vicinity of synthetic jet orifice 241 μm in diameter issuing into confined geometry. Comparisons between experimental and numerical results on the streamwise component of velocity profiles at the orifice exit and along the centerline of the pulsating jet in microchannel as well as the location of vortex core indicate that there is good agreement, thereby demonstrating that the moving mesh algorithm developed is valid.
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 09-2006
Publisher: Informa UK Limited
Date: 02-01-2018
Publisher: SAGE Publications
Date: 03-2012
Abstract: In the numerical study, investigation of bubbly flow requires deep understanding of complex hydrodynamics under various flow conditions. In order to simulate the bubble behaviour in conjunction with suitable bubble coalescence and bubble breakage kernels, direct quadrature method of moments (DQMOM) has been applied and validated instead. To examine the predictive results from DQMOM model, the validation has been carried out against experimental data of Lucas et al. (2005) and Prasser et al. (2007) measured in the Forschungszentrum Dresden-Rossendorf FZD facility. Numerical results showed good agreement against experimental data for the local and axial void fraction, bubble size distribution and interfacial area concentration profiles. Encouraging results demonstrates the prospect of the DQMOM two-fluid model against flow conditions with wider range of bubble sizes and rigorous bubble interactions. Moreover, moment sensitivity study also has been carried out to carefully assess the performance of the model. In order to perform the moment sensitivity test three different moment criteria has chosen – as 4 moments, 6 moments and 8 moments. Close agreement between the predictions and measurement was found and it appeared that increasing the number of moments does not have much significance to improve the conformity with experimental data. Nonetheless, increasing the number of moments merely contribute to perform the calculation expensive in terms of computational resource and time. Based on the present study, this preliminary assessment has definitely served to demonstrate and exploit DQMOM model's capabilities to handle wider range of bubble sizes as well as moment resolution required to achieve moment independent solution.
Publisher: Elsevier BV
Date: 2004
Publisher: Wiley
Date: 18-04-2008
DOI: 10.1002/AIC.11503
Publisher: MDPI AG
Date: 25-02-2019
DOI: 10.3390/FIRE2010011
Abstract: Recent high-profile building fires involving highly-combustible external cladding panels in Australia as well as Dubai, China, and the United Kingdom have created a heightened awareness by the public, government, and commercial entities to act on the risks associated with non-compliant building structures. In this paper, a database of fire events involving combustible aluminium composite panels was developed based on (i) review of relevant major fire events in Australia and other countries, and (ii) numerical simulation of the ignitability, fire spread, and toxic emissions associated with composite panels. Through the application of large-eddy-simulation (LES)-based computational fire field models, the associated risks for a standardized two-storey building with external cladding was considered in this study. A total of sixteen simulation cases with different initial sizes of the fire and different air cavity widths in the exterior cladding assembly were examined to investigate the tolerable situations and their influences. It was discovered that for most cases, with an initial fire size greater than 400 kW/m−2, the fire will spread from the first to second floor before the allowed egress time period.
Publisher: Elsevier BV
Date: 12-2017
Publisher: MDPI AG
Date: 12-10-2019
DOI: 10.3390/APP9204275
Abstract: With the escalating production of automobiles, energy efficiency and environmental friendliness have always been a major concern in the automotive industry. In order to effectively lower the energy consumption of a vehicle, it is essential to develop air-conditioning systems that can make good use of combustion waste heat. Ejector refrigeration systems have become increasingly popular for this purpose due to their energy efficiency and ability to recycle waste heat. In this article, the elements affecting the performance of a typical ejector refrigeration system have been explored using both experimental and numerical approaches. For the first time, the internal flow structure was characterized by means of comprehensive numerical simulations. In essence, three major sections of the steam ejector were investigated. Two energy processes and the shock-mixing layer were defined and analyzed. The results indicated that the length of the choking zone directly affects the entertainment ratio under different primary fluid temperature. The optimum enterainment ratio was achieved with 138 °C primary fluid temperature. The shock-mixing layer was greatly affected by secondary fluid temperature. With increasing of back pressure, the normal shock gradually shifted from the diffuser towards the throat, while the shock train length remains lunchanged.
Publisher: Elsevier BV
Date: 07-2012
Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/5452085
Abstract: The cold neutron source (CNS) system of the Open Pool Australian Light-Water (OPAL) reactor is a 20 L cryogenically cooled liquid deuterium thermosiphon system. The CNS is cooled by forced convective helium which is held at room temperature during stand-by (SO) mode and at ~20 K during normal operation (NO) mode. When helium cooling stops, the reactor is shut down to prevent the moderator cell from overheating. This computational fluid dynamics (CFD) study aims to determine whether the combined effects of conduction and natural convection would provide sufficient cooling for the moderator cell under the influence of reactor decay heat after reactor shutdown. To achieve this, two commercial CFD software packages using an identical CFD mesh were first assessed against an experimental heat transfer test of the CNS. It was found that both numerical models were valid within the bounds of experimental uncertainty. After this, one CFD model was used to simulate the thermosiphon transient condition after the reactor is shut down. Two independent shutdown conditions of different decay-heat power profiles were simulated. It was found that the natural convection and conduction cooling in the thermosiphon were sufficient for dissipating both decay-heat profiles, with the moderator cell remaining below the safe temperature of 200°C.
Publisher: Informa UK Limited
Date: 08-2000
Publisher: MDPI AG
Date: 08-07-2022
Abstract: The increasing popularity of lithium-ion battery systems, particularly in electric vehicles and energy storage systems, has gained broad research interest regarding performance optimization, thermal stability, and fire safety. To enhance the battery thermal management system, a comprehensive investigation of the thermal behaviour and heat exchange process of battery systems is paramount. In this paper, a three-dimensional electro-thermal model coupled with fluid dynamics module was developed to comprehensively analyze the temperature distribution of battery packs and the heat carried away. The computational fluid dynamics (CFD) simulation results of the lumped battery model were validated and verified by considering natural ventilation speed and ambient temperature. In the artificial neural networks (ANN) model, the multilayer perceptron was applied to train the numerical outputs and optimal design of the battery setup, achieving a 1.9% decrease in maximum temperature and a 4.5% drop in temperature difference. The simulation results provide a practical compromise in optimizing the battery configuration and cooling efficiency, balancing the layout of the battery system, and safety performance. The present modelling framework demonstrates an innovative approach to utilizing high-fidelity electro-thermal/CFD numerical inputs for ANN optimization, potentially enhancing the state-of-art thermal management and reducing the risks of thermal runaway and fire outbreaks.
Publisher: MDPI AG
Date: 25-08-2021
Abstract: Room temperature vulcanized (RTV) silicone rubber filled with aluminum trihydrate (ATH) is substantially engaged in electrical outdoor insulation applications. The pristine silicone rubber is highly combustible. ATH filled silicone rubber offers excellent electrical insulation but lacks in providing adequate flame retardancy. This short communication reports the novel results on improved flame retardancy of pristine and ATH filled silicone rubber whilst retaining the electrical insulation properties to a great extent. Results suggest that the presence of only one percent of graphene nanoplatelets with ATH sharply reduces the heat release rate and rate of smoke release. A minor reduction in dielectric breakdown strength and volume resistivity is noticed. Furthermore, permittivity and dielectric loss at power frequency suggest that a marginal 1% concentration of nanoplatelet with ATH is an excellent approach to fabricate flame retardant silicone rubber with an acceptable electrical insulation level.
Publisher: Hindawi Limited
Date: 2011
DOI: 10.1155/2011/304983
Publisher: AIP Publishing
Date: 09-2012
DOI: 10.1063/1.4753944
Abstract: Large-eddy simulations examining natural convection in an enclosed cavity with the simultaneous presence of laminar, transitional, and turbulent flow regimes were conducted. The Rayleigh number based on height of the cavity is 4.6 × 1010. Different dynamic global-coefficient procedures to compute the Vreman [A. W. Vreman, “An eddy-viscosity subgrid-scale model for turbulent shear flow: Algebraic theory and applications,” Phys. Fluids 16, 3670 (2004)] model coefficient were implemented for the subgrid-scale tensors in both the momentum and energy equations. Based on comparison with experimental and existing numerical data, it is shown that the dynamic model derived from the “global equilibrium” hypothesis gives favorable results in the mean flow and turbulence quantities. Nevertheless, because of higher subgrid-scale dissipation, transition to a turbulent flow is postponed when the Vreman model coefficient is either uniform or determined dynamically using the Germano identity approach. This suggests that much finer grid is desired when using these models in order to better capture the weak transitional boundary layer. Further, by exploring the instantaneous flow dynamics, it is demonstrated that characteristics of the coherent structures which resemble streaks in forced convection boundary layers are somewhat dissimilar in the different models.
Publisher: IOP Publishing
Date: 09-2016
Publisher: Elsevier BV
Date: 09-2007
Publisher: American Chemical Society (ACS)
Date: 31-10-2018
Abstract: A novel three-dimensional (3D) epoxy/graphene nanosheet/hydroxylated boron nitride (EP/GNS/BNOH) hybrid aerogel was successfully fabricated in this study. This was uniquely achieved by constructing a well-defined and interconnected 3D network architecture. The manufacturing process of EP/GNS/BNOH involved a simple one-pot hydrothermal strategy, followed by the treatment of freeze-drying and high-temperature curing. In comparison with EP/GNS-3, EP/GNS/BNOH-3 demonstrated improvement of 97% for compressive strength at 70% strain. Through compression tests, fracture occurred for EP/GNS-3 at ninth compression cycles, whereas EP/GNS/BNOH-3 retained its original form after twenty compression cycles, with a residual height of 97% (i.e., only 3% reduction). By the addition of BNOH in the polymer matrix, the dynamic heat transfer and dissipation rates of EP/GNS/BNOH aerogels were also considerably reduced, indicating that the aerogel with BNOH additive possessed excellent thermal insulation properties. Thermogravimetric analysis results revealed that the thermal stabilities of EP/GNS and EP/GNS/BNOH aerogels were improved with increasing loading of EP, and EP/GNS/BNOH aerogels exhibited a better thermal stability at high temperatures. Through the elevated levels attained in the compressive strength, superelasticity, and thermal resistance, EP/GNS/BNOH aerogels has the great potential of being a very effective thermal insulation material to be utilized across a board range of applications in building, automotive, spacecraft, and mechanical systems.
Publisher: Springer Science and Business Media LLC
Date: 12-10-2020
Publisher: Elsevier
Date: 2013
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 04-2018
Publisher: Cambridge University Press (CUP)
Date: 14-05-2008
DOI: 10.1017/S0022112008001080
Abstract: A modified Lundgren model is applied for the description of stationary bathtub vortices in a viscous liquid with a free surface. Laminar liquid flow through the circular bottom orifice is considered in the horizontally unbounded domain. The liquid is assumed to be undisturbed at infinity and its depth is taken to be constant. Three different drainage regimes are studied: (i) subcritical, where whirlpool dents are less than the fluid depth (ii) critical, where the whirlpool tips touch the outlet orifice and (iii) supercritical, where surface vortices entrain air into the intake pipe. Particular attention is paid to critical vortices the condition for their existence is determined and analysed. The influence of surface tension on subcritical whirlpools is investigated. Comparison of results with known experimental data is discussed.
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 06-2003
Publisher: Elsevier BV
Date: 12-2012
Publisher: American Society of Mechanical Engineers
Date: 14-07-2013
DOI: 10.1115/HT2013-17400
Abstract: Buoyancy-driven flows in an asymmetrically heated open-ended channel which occur in façade and roof building-integrated photovoltaic systems were investigated using large-eddy simulation. The channel inclination angle was varied from 30° to 90° to the horizontal, whereas the channel height-to-width aspect ratio remained at 20. In each case, a uniform heat flux was applied along the top wall whereas the bottom wall was assumed to be adiabatic. It is shown that typical dynamics of large-scale structures in the flow and thermal fields of natural convection in the channels are successfully modeled numerically by the use of LES. The effects of varying the inclination angle on the heat transfer in the channel are explored by examining the mean flow fields and in addition, the effects of radiation have been considered. Both experimental and numerical results show that open-ended channels with low inclination angles are characterized by a low chimney effect which leads to a decreased flow rate and a delay in transition to turbulence, thereby decreasing the heat transfer coefficient and leading to higher temperatures on the heated wall. A correlation describing the local Nusselt number in the channel is also developed in order to characterize the global heat transfer behavior.
Publisher: American Society of Mechanical Engineers
Date: 07-07-2013
Abstract: Current devices have been reported to approach 1 MW/m2 so that current heat dissipation devices will not be able to cope with increasing heat flux. It has therefore been proposed that in order to manage the ever-increasing heat rejection demands, it will be necessary to have cooling fluid flowing through micro-channels in the microchip itself. Since laminar flow is likely to result for reasonable pressure drops in these micro-channels, the heat transfer rate will need to be enhanced if this approach is to be successfully used. Synthetic jets, which are the main focus of this research, generate vortex structures which disrupt the flow. They have, therefore, been proposed as a means of providing mixing, thereby augmenting the heat transfer potential of the fluid in the micro-channel. A two-dimensional computational model has been developed to investigate the cooling effect of a synthetic jet interacting with a turbulent cross-flow in a micro-channel. Validation of the hydrodynamics feature of the flow was done by comparing numerical results against existing experimental results. A parametric study was performed on a fixed geometry by using a constant wall temperature to investigate the effect of operating frequency of the synthetic jet actuator coupling with different flow rates in the micro-channel. The operating frequencies of the jet were simulated at 1000 Hz, 1500 Hz and 2000 Hz while the cross flows vary from 0 to 10 m/s. In general, the flow structures in the micro-channel were shown to be greatly disrupted when the synthetic jet actuator was turned on. However, the heat transfer enhancement due to the operation of the synthetic jet reduces as the cross flow increases. The frequency of the diaphragm oscillation has a large influence on the distance between the adjacent vortices and therefore on the average flow rate in the micro-channel. The near wall Nusselt Number was calculated in order to compare the effects of operating frequency of the jet and flow rate in the micro-channel. The jet Reynolds number was increased by 50% when the actuator frequency was increased from 1000 Hz to 1500 Hz while the heat transfer enhancement was increased by 21%. Further increment of actuator frequency from 1000 Hz to 2000 Hz resulted in a doubled jet Reynolds number while the heat transfer enhancement was improved by 66%. The heat transfer enhancement showed greater improvement when the actuator operating at 2000 Hz.
Publisher: Begell House
Date: 2012
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 03-2002
Publisher: Elsevier BV
Date: 04-2019
Publisher: Springer Science and Business Media LLC
Date: 10-06-2019
Publisher: ASTM International
Date: 2011
DOI: 10.1520/JAI103374
Publisher: International Union of Crystallography (IUCr)
Date: 25-03-2022
DOI: 10.1107/S1600576722002084
Abstract: Ultra-small-angle neutron scattering (USANS) and small-angle neutron scattering (SANS) measurements, covering length scales from micrometres to nanometres, were made to investigate the structure of nanodiamonds (NDs) and their suspensions. These nanodiamonds were produced by two different techniques, namely by the detonation method and by the laser ablation of a carbon–hydrocarbon mixture. The (U)SANS results indicated the presence of structures four orders of magnitude larger than the dimensions of a single ND particle, consisting of aggregations of ND particles. This aggregation of the ND particles was studied by employing the contrast variation technique. Two different solvents, namely H 2 O and dimethyl sulfoxide (and their deuterated counterparts), were used to understand the role of hydrogen in the shape and size of the aggregates. The analysis of experimental data from SANS measurements also reveals the ND particles to have an ellipsoidal structure. Using a defined shape model and the SANS contrast variation technique, it was possible to characterize the non-diamond outer shell of the particles and determine the outer layer thickness. This clarification of the structure of the NDs will allow better preparation of suspensions/s les for various applications. Understanding the structure of NDs at multiple length scales also provides crucial knowledge of particle–particle interaction and its effect on the aggregation structures.
Publisher: Elsevier BV
Date: 04-2016
Publisher: Elsevier
Date: 2009
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.JHAZMAT.2019.120952
Abstract: MXene/chitosan nanocoating for flexible polyurethane foam (PUF) was prepared via layer-by-layer (LbL) approach. MXene (Ti
Publisher: Elsevier BV
Date: 11-2006
Publisher: MDPI AG
Date: 29-06-2023
DOI: 10.3390/MOLECULES28135100
Abstract: The effect of varying the weight percentage composition (wt.%) of low-cost expandable graphite (EG), ammonium polyphosphate (APP), fibreglass (FG), and vermiculite (VMT) in polyurethane (PU) polymer was studied using a traditional intumescent flame retardant (IFR) system. The synergistic effect between EG, APP, FG, and VMT on the flame retardant properties of the PU composites was investigated using SEM, TGA, tensile strength tests, and cone calorimetry. The IFR that contained PU composites with 40 wt.% EG displayed superior flame retardant performance compared with the composites containing only 20 w.t.% or 10 w.t.% EG. The peak heat release rate, total smoke release, and carbon dioxide production from the 40 wt.% EG s le along with APP, FG, and VMT in the PU composite were 88%, 93%, and 92% less than the PU control s le, respectively. As a result, the synergistic effect was greatly influenced by the compactness of the united protective layer. The PU composite suppressed smoke emission and inhibited air penetrating the composite, thus reducing reactions with the gas volatiles of the material. SEM images and TGA results provided positive evidence for the combustion tests. Further, the mechanical properties of PU composites were also investigated. As expected, compared with control PU, the addition of flame-retardant additives decreased the tensile strength, but this was ameliorated with the addition of FG. These new PU composite materials provide a promising strategy for producing polymer composites with flame retardation and smoke suppression for construction materials.
Publisher: Begellhouse
Date: 2012
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 10-2007
Publisher: Elsevier BV
Date: 06-2014
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 08-2007
Publisher: Informa UK Limited
Date: 31-08-2007
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 03-2014
Publisher: Elsevier BV
Date: 11-2006
Publisher: Springer Science and Business Media LLC
Date: 17-01-2014
Publisher: Informa UK Limited
Date: 07-2002
Publisher: Elsevier BV
Date: 10-2007
Publisher: American Society of Mechanical Engineers
Date: 09-11-2012
Abstract: The motion and transport of bubbles in fluid flows have many engineering applications. The rise of a bubble has been a point of interest for both numerical and experimental studies. Various tracking methodologies have been developed, including markers, level sets and volume tracking. In order to validate numerical models of bubble flow, detailed experimental data describing the transient bubble shape is needed. This is best found from a 2D comparison rather than 3D experiment because computational resources for determining an accurate shape can be maximized. No real full time shape and subsequent deformation of this 2D bubble has yet been demonstrated. In this paper 2D bubble experiments have been conducted, in which a single bubble has been injected inside a close-walled tank and the rising of the bubble has been captured through a high speed camera. This data is now being used as a benchmark for numerical interface capturing and two phase flow methodology validations.
Publisher: Elsevier BV
Date: 08-2004
Publisher: Informa UK Limited
Date: 05-12-2007
Publisher: Elsevier BV
Date: 08-2018
Publisher: MDPI AG
Date: 26-01-2018
DOI: 10.3390/NANO8020070
Abstract: High-performance poly(1,4-butylene terephthalate) (PBT) nanocomposites have been developed via the consideration of phosphorus-containing agents and amino-carbon nanotube (A-CNT). One-pot functionalization method has been adopted to prepare functionalized CNTs via the reaction between A-CNT and different oxidation state phosphorus-containing agents, including chlorodiphenylphosphine (DPP-Cl), diphenylphosphinic chloride (DPP(O)-Cl), and diphenyl phosphoryl chloride (DPP(O3)-Cl). These functionalized CNTs, DPP(Ox)-A-CNTs (x = 0, 1, 3), were, respectively, mixed with PBT to obtain the CNT-based polymer nanocomposites through a melt blending method. Scanning electron microscope observations demonstrated that DPP(Ox)-A-CNT nanoadditives were homogeneously distributed within PBT matrix compared to A-CNT. The incorporation of DPP(Ox)-A-CNT improved the thermal stability of PBT. Moreover, PBT/DPP(O3)-A-CNT showed the highest crystallization temperature and tensile strength, due to the superior dispersion and interfacial interactions between DPP(O3)-A-CNT and PBT. PBT/DPP(O)-A-CNT exhibited the best flame retardancy resulting from the excellent carbonization effect. The radicals generated from decomposed polymer were effectively trapped by DPP(O)-A-CNT, leading to the reduction of heat release rate, smoke production rate, carbon dioxide and carbon monoxide release during cone calorimeter tests.
Publisher: SAGE Publications
Date: 06-2010
Abstract: In this study, the internal phase distributions of gas-liquid bubbly flow in a horizontal pipe have been predicted using the population balance model based on Average Bubble Number Density approach. Four flow conditions with average gas volume fraction ranging from 4.4% to 20% have been investigated. Predicted local radial distributions of void fraction, interfacial area concentration and gas velocity have been validated against the experimental data. In general, satisfactory agreements between predicted results and measured values have been achieved. For high superficial gas velocity, it has been ascertained that peak local void fraction of 0.7 with interfacial area concentration of 800 m −1 can be encountered near the top wall of the pipe. Some discrepancies have nonetheless been found between the numerical and experimental results at certain locations of the pipe. The insufficient resolution of the turbulent model in fully accommodating the strong turbulence in the current pipe orientation and the inclusion of additional interfacial force such as the prevalent bouncing force among bubbles remain some of the outstanding challenging issues need to be addressed in order to improve the prediction of horizontal gas-liquid bubbly flow.
Publisher: Informa UK Limited
Date: 02-08-2017
Publisher: Elsevier BV
Date: 2014
Publisher: SAGE Publications
Date: 12-2012
Publisher: Elsevier BV
Date: 09-2007
Publisher: Informa UK Limited
Date: 07-2002
Publisher: Elsevier BV
Date: 03-2008
Publisher: MDPI AG
Date: 12-07-2018
DOI: 10.3390/APP8071132
Abstract: In this paper, the plasmonic resonant absorption of gold nanorods (GNRs) and GNR solutions was studied both numerically and experimentally. The heat generation in clustered GNR solutions with various concentrations was measured by exposing them to Near Infrared (NIR) light in experiment. Correspondingly, calculations based on the discrete-dipole approximation (DDA) revealed the same relationship between the maximum absorption efficiency and the nanorod orientation for the incident radiation. Additionally, both the plasmonic wavelength and the maximum absorption efficiency of a single nanorod were found to increase linearly with increasing aspect ratio (for a fixed nanorod volume). The wavelength of the surface plasmonic resonance (SPR) was found to change when the gold nanorods were closely spaced. Specifically, both a shift and a broadening of the resonance peak were attained when the distance between the nanorods was set to about 50 nm or less. The absorbance spectra of suspended nanorods at various volume fractions also showed that the plasmonic wavelength of the nanorods solution was at 780 ± 10 nm, which was in good agreement with the computational predictions for coupled side-by-side nanorods. When heated by NIR light, the rate of increase for both the temperature of solution and the absorbed light diminished when the volume fraction of suspended nanorods reached a value of 1.24×10−6. This matches with expectations for a partially clustered suspension of nanorods in water. Overall, this study reveals that particle clustering should be considered to accurately gauge the heat generation of the GNR hyperthermia treatments.
Publisher: Elsevier BV
Date: 05-2005
Publisher: Informa UK Limited
Date: 27-01-2021
Publisher: AIP
Date: 2010
DOI: 10.1063/1.3366467
Publisher: Elsevier BV
Date: 07-2018
Publisher: Springer Science and Business Media LLC
Date: 12-2010
DOI: 10.1007/S13246-010-0050-4
Abstract: Numerical simulation is performed to demonstrate that hemodynamic factors are significant determinants for the development of a vascular pathology. Experimental measurements by particle image velocimetry are carried out to validate the credibility of the computational approach. We present a study for determining complex flow structures using the case of an anatomically realistic carotid bifurcation model that is reconstructed from medical imaging. A transparent silicone replica of the artery is developed for in-vitro flow measurement. The dynamic behaviours of blood through the vascular structure based on the numerical and experimental approaches show good agreement.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Trans Tech Publications, Ltd.
Date: 10-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.444-445.1579
Abstract: The Wall Adpating Local Eddy Viscosity (WALE) subgrid-scale turbulence model was adopted for an in-house large eddy simulation (LES) fire code in which the turbulence is fully coupled combustion and radiation models. The traditional Smagorinsky subgrid-scale model accounts only strain rate of the turbulent structure while the WALE model considers both the strain and the rotation rates. Furthermore, the WALE model automatically recovers the near wall-scaling for the eddy viscosity hence more adaptive for wall bounded flows.A 15 m long test hall fire was reconstructed by the in-house fire code with 1.5 MW fire source. The performance of the WALE model was assessed by comparingpredicted transient gas temperatures and velocities at various spatial locations.
Publisher: Springer Science and Business Media LLC
Date: 13-01-2020
Publisher: American Chemical Society (ACS)
Date: 04-08-2018
DOI: 10.1021/ACS.LANGMUIR.8B01457
Abstract: Gold nanoparticle (GNP) aggregation has a strong influence on the plasmonic resonance and hence the effectiveness in various photothermal applications. In relation to this, a comprehensive numerical model is developed to simulate and characterize the GNP aggregation process at various particle volume fractions and base fluid pH levels. Computational fluid dynamics techniques are utilized to model the base fluid, whereas discrete phase modeling is adopted in determining the nanoparticle trajectories. Two-way coupling is implemented to handle the particle-fluid interactions. Discrete dipole approximation approach is utilized to further examine the absorption and scattering efficiency of various GNP aggregate structures. At lower particle volume fraction, short chain-like structures are formed in the particle aggregation process, with a more complex interconnected "particle network" structure formed at higher particle volume fractions. With the three base fluid pH levels investigated, GNP aggregates are more compact with larger fractal dimensions and higher mean coordination numbers at pH = 3.5, whereas a more "loose" structure formed at pH = 6.7 and 9.4 because of larger electrostatic repulsive forces as a result of changes in the zeta potential and Debye length of the GNPs. Among the typical GNP aggregate structures characterized in this paper, the chain-like tetramer demonstrates the highest absorption efficiency of 1.83 at 700 nm wavelength-comparable to the plasmonic resonance of a nanorod-which lies in the optical window of biological tissue. Predictions of GNP optical properties are found to be in good agreement with the published experimental data.
Publisher: IEEE
Date: 10-2016
Publisher: Wiley
Date: 2005
DOI: 10.1002/AIC.10297
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5LC90125A
Publisher: Elsevier BV
Date: 08-2015
Publisher: MDPI AG
Date: 09-04-2019
DOI: 10.3390/APP9071476
Abstract: Nanofluids can be considered as engineered colloidal suspensions of nanometer-sized particles in a base fluid of water, ethylene glycol, or oil [...]
Publisher: Elsevier BV
Date: 2018
Publisher: Informa UK Limited
Date: 05-2004
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 04-2012
Publisher: Wiley
Date: 09-1990
Publisher: SAGE Publications
Date: 25-12-2016
Abstract: In order to accurately predict the thermal hydraulic of two-phase gas–liquid flows with heat and mass transfer, special numerical considerations are required to capture the underlying physics: characteristics of the heat transfer and bubble dynamics taking place near the heated wall and the evolution of the bubble size distribution caused by the coalescence, break-up, and condensation processes in the bulk subcooled liquid. The evolution of the bubble size distribution is largely driven by the bubble coalescence and break-up mechanisms. In this paper, a numerical assessment on the performance of six different bubble coalescence and break-up kernels is carried out to investigate the bubble size distribution and its impact on local hydrodynamics. The resultant bubble size distributions are compared to achieve a better insight of the prediction mechanisms. Also, the void fraction, bubble Sauter mean diameter, and interfacial area concentration profiles are compared against the experimental data to ensure the validity of the models applied.
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 02-2019
Publisher: AIP
Date: 2010
DOI: 10.1063/1.3452294
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 09-2003
Publisher: Informa UK Limited
Date: 20-09-2016
Publisher: Hindawi Limited
Date: 2012
DOI: 10.1155/2012/610610
Publisher: Elsevier BV
Date: 04-2016
Publisher: Elsevier BV
Date: 12-2019
Start Date: 2016
End Date: 12-2018
Amount: $276,688.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2003
End Date: 11-2007
Amount: $69,099.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2013
End Date: 06-2015
Amount: $120,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 11-2004
End Date: 11-2007
Amount: $70,668.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2015
End Date: 06-2016
Amount: $152,436.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2015
End Date: 06-2018
Amount: $266,300.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2008
End Date: 07-2011
Amount: $235,944.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2005
End Date: 06-2008
Amount: $178,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2005
End Date: 10-2007
Amount: $111,115.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2022
End Date: 07-2025
Amount: $332,338.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2009
End Date: 12-2012
Amount: $245,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2024
End Date: 04-2029
Amount: $4,999,700.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2022
End Date: 07-2027
Amount: $5,000,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 11-2014
End Date: 11-2016
Amount: $134,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2008
End Date: 12-2010
Amount: $255,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2018
End Date: 07-2023
Amount: $4,272,072.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2024
End Date: 02-2031
Amount: $35,000,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2007
End Date: 12-2009
Amount: $30,900.00
Funder: Australian Research Council
View Funded Activity