ORCID Profile
0000-0002-6812-9148
Current Organisations
American University of the Middle East
,
University of Adelaide
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Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 06-2016
Publisher: Springer Science and Business Media LLC
Date: 27-02-2021
Publisher: MDPI AG
Date: 13-06-2023
DOI: 10.3390/WEVJ14060156
Abstract: Conventional transportation systems are facing many challenges related to reducing fuel consumption, noise, and pollutants to satisfy rising environmental and economic criteria. These requirements have prompted many researchers and manufacturers in the transportation sector to look for cleaner, more efficient, and more sustainable alternatives. Powertrains based on fuel cell systems could partially or completely replace their conventional counterparts used in all modes of transport, starting from small ones, such as scooters, to large mechanisms such as commercial airplanes. Since hydrogen fuel cells (HFCs) emit only water and heat as byproducts and have higher energy conversion efficiency in comparison with other conventional systems, it has become tempting for many scholars to explore their potential for resolving the environmental and economic concerns associated with the transportation sector. This paper thoroughly reviews the principles and applications of fuel cell systems for the main transportation schemes, including scooters, bicycles, motorcycles, cars, buses, trains, and aerial vehicles. The review showed that fuel cells would soon become the powertrain of choice for most modes of transportation. For commercial long-rage airplanes, however, employing fuel cells will be limited due to the replacement of the axillary power unit (APU) in the foreseeable future. Using fuel cells to propel such large airplanes would necessitate redesigning the airplane structure to accommodate the required hydrogen tanks, which could take a bit more time.
Publisher: Springer Science and Business Media LLC
Date: 14-09-2020
Publisher: Springer Science and Business Media LLC
Date: 11-12-2018
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 02-2018
Publisher: ASME International
Date: 14-05-2019
DOI: 10.1115/1.4043212
Abstract: The flow around a rectangular cylinder mounted in the vicinity of a hot wall is numerically studied at a Reynolds number of 200. While the cylinder chord-to-height ratio C/W is varied from 2 to 10, the gap distance G from the wall to the cylinder is changed from 0.25 to 6.25. The focus of this study is given on the dependence of G/W and C/W on the heat transfer from the wall and associated physics. The variation in the Strouhal number is presented as a function of C/W. It is observed that the effect of G/W on the vortex dynamics and heat transfer is much more than that of C/W. Based on the dependence of the vortex dynamics and heat transfer on G/W, we have identified four distinct flows: no vortex street flow (G/W 0.75), single-row vortex street flow (0.75 ≤ G/W ≤ 1.25), inverted two-row vortex street flow (1.25 G/W ≤ 2.5), and two-row vortex street flow (G/W 2.5). At the single-row vortex street flow, the two opposite-sign vortices appearing in a jetlike flow carry heat from the wall to the wake and then to the freestream. The maximum heat transfer is achieved at the single-row vortex street flow and 8% increase occurs at C/W = 2, G/W = 0.75–1.25.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 12-2021
Publisher: Springer Science and Business Media LLC
Date: 15-06-2020
Publisher: Springer Science and Business Media LLC
Date: 16-10-2020
Publisher: AIP Publishing
Date: 07-2022
DOI: 10.1063/5.0096149
Abstract: The multi-mode transition and vortex structures in the vortex-induced vibration (VIV) of a near-wall flexible cylinder under different yaw angles are investigated through three-dimensional direct numerical simulation. Yaw angles α = 0°–60°, gap ratio G/D = 0.8, and Re = 500 are adopted. With the increase in α, the dominated vibration mode decreases from the 6th to 1st mode in the in-line (IL) direction and the 3rd to 2nd mode in the cross-flow (CF) direction. For the IL vibration, no mode transition occurs at α = 0°, whereas frequently mode transition is observed at α & 0°, due to the intermittent participation and spanwise competition of different modes, thus showing an intensified traveling-wave characteristic. For the CF vibration, mode transition is not excited at any α case even with spanwise mode competitions, due to the significant weight of the dominated mode, thus showing a strong standing-wave characteristic. The asymmetrical distributions of vibration displacements and force coefficients are established because of irregular energy transfer along the span. The spanwise vortex tubes at α = 0°–30° are separated into several cells associated with the dominated vibration mode, showing a locally parallel vortex shedding. However, positively yawed and negatively yawed vortex shedding are observed at α = 45° and 60°, respectively. The vortex strengths vary along the cylinder, where large-scale and small-scale vortices are observed at the CF anti-node and node planes, respectively. The independence principle is only valid at α & 15° for predicting the multi-mode vibrations and hydrodynamics, significantly reduced from that of α & 45° in the wall-free case or the mono-mode VIV case.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.ISATRA.2019.06.026
Abstract: In the 21th century water management using new technologies is a must due to the rapid growth of population, drought, and water scarcity. The Internet of Things (IoT) system with wireless devices can be employed to achieve this requirement. This paper introduces an innovative technique of multi-intelligent control system (MICS) of a water pump and a pump station, which is practically designed, set up, and used in an agricultural sector. The main component of MICS consists of three control systems, including the electro-pump controller, water level in reservoir and alarm control system. The entire system is governed by the IoT technology and operated via SMS or ringtone, which is manageable from anywhere at any time. A soft starter mechanism was designed and considered for running the electro-pump to eliminate the electrical shocks and mechanical stresses. In the proposed control system, a 4-state switch was designed and employed, which facilitates running and operating the system manually, automatically, using IoT state, and finally in off mode state. Description of the control and power circuits of the system are explained in detail. MICS is a very reliable system and provides a convenient and satisfactory solution for water management in the agricultural and industrial sectors as well as domestic consumption. The model is applied to a practical case study to demonstrate the effectiveness of the proposed control system. It is found that in addition to increasing the efficiency and productivity of the water management system, up to 60% of water can be saved by employing MICS via IoT.
Publisher: AIP Publishing
Date: 05-2014
DOI: 10.1063/1.4879275
Abstract: Vortex Induced Vibrations (VIVs) play a key role in a wide range of engineering applications including the extraction of renewable energy. In this paper, numerical studies of the phenomenon of VIV were conducted to investigate the flow behaviour around two identical circular cylinders. The upstream cylinder was located in the vicinity of a rigid wall and downstream one was mounted on an elastic support with one degree of freedom. The Reynolds number based on the cylinder's diameter was kept constant at 8700, while the separation between the upstream cylinder and the wall was varied. The results show that this separation distance known as the gap ratio has a significant effect on the dynamic behaviour of the upstream and downstream cylinders. Accordingly, the interaction of shear layers between the upstream cylinder and the rigid wall has a strong influence on the vortex dynamics of both cylinders, in particular, when the upstream cylinder was mounted close to the wall. In this arrangement, a jet flow produced in the wake of the upstream cylinder significantly affects the vortex shedding frequency, and the lift and drag coefficients of both cylinders. This can alter the dynamic response of the downstream cylinder and theoretical efficiency of the VIV power.
Publisher: MDPI AG
Date: 05-07-2023
DOI: 10.3390/PR11072015
Abstract: Nanofluids have gained attention for their potential to solve overheating problems in various industries. They are a mixture of a base fluid and nanoparticles dispersed on the nanoscale. The nanoparticles can be metallic, ceramic, or carbon based, depending on the desired properties. While nanofluids offer advantages, challenges such as nanoparticle agglomeration, stability, and cost effectiveness remain. Nonetheless, ongoing research aims to fully harness the potential of nanofluids in addressing overheating issues and improving thermal management in different applications. The current study is concerned with the fluid flow and heat transfer characteristics of different nanofluids using different types of nanoparticles such as Al2O3, SiO2, and ZnO mixed with different base fluids. Pure water and ethylene glycol–water (EG–H2O) mixtures at different EG–H2O ratios (ψ = 0%, 10%, 30%, 40%) are used as the base fluid. Furthermore, a rectangular microchannel heat sink is used. Mesh independent study and validation are performed to investigate the current model, and a good agreement is achieved. The numerical analysis evaluates the influence on the heat transfer coefficient and flow characteristics of nanofluids for Reynolds numbers 500 to 1200 at a 288 K inlet flow temperature. The results show that ZnO nanofluid and 40% EG–H2O increase the heat transfer coefficient by 63% compared to ZnO–H2O nanofluid obtained at Re = 1200 and φ = 5%. Conversely, the pressure drop by ZnO is nearly double that obtained by Al2O3 and SiO2.
Publisher: Springer Science and Business Media LLC
Date: 14-10-2019
No related grants have been discovered for Javad Farrokhi Derakhshandeh.