Article
Engineering, Multidisciplinary
Hassnia Hajji, Lioua Kolsi, Kaouther Ghachem, Chemseddine Maatki, Ahmed Kadhim Hussein, Mohamed Naceur Borjini
Summary: This study presents two and three-dimensional numerical simulations of flow through sudden expansion and contraction microchannels. Results show the appearance of a separate vortex in the corner after sudden expansion for low Reynolds numbers, with the vortex separation length increasing for high Reynolds numbers. The three-dimensional character of flow is more pronounced for higher Reynolds numbers.
ALEXANDRIA ENGINEERING JOURNAL
(2021)
Article
Engineering, Multidisciplinary
Praveen J. Sanga, Arbind Kumar, Sabin K. Mishra
Summary: A numerical study was conducted to investigate the thermal and flow fields of a two-dimensional vented cavity under forced convection turbulent flow. The study found that the top curved wall surface has significant effects on heat transfer performance in different configurations of inlet and outlet ports. Increasing the height of the curved surface enhances heat transfer, but also leads to relatively high pressure drop. On the other hand, the semi-elliptical top surface cavity with inlet and outlet ports positioned on the same axis exhibits better heat transfer performance.
ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS
(2022)
Article
Mechanics
Baiyang Song, Huan Ping, Hongbo Zhu, Dai Zhou, Yan Bao, Yong Cao, Zhaolong Han
Summary: In this study, the impact of incoming turbulence on the flow dynamics behind a single main cylinder was investigated using direct numerical simulations. The results showed that the incoming turbulence significantly affected the drag and lift coefficients and accelerated the turbulent transition of shear layers.
Article
Engineering, Multidisciplinary
As'ad Alizadeh, Azher M. Abed, Hussein Zekri, Ghassan Fadhil Smaisim, Bahram Jalili, Pooya Pasha, Davood Domiri Ganji
Summary: This investigation focuses on the heat removal from surfaces with high heat flux, utilizing tabulators and parts with a unique geometry as a solution. The primary hypothesis is to enhance fluid heat transfer through increased turbulence and heat transfer area, achieved by the simultaneous use of a turbulator and increased contact surface. The research applies the limited volume method and Ansys Fluent software to solve governing equations and compares turbulators SLT and TRT with others in terms of Nusselt number and friction coefficient reduction.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
Shou-Shing Hsieh, Ching-Feng Huang, Jian-Siang Pan
Summary: This study experimentally investigated the convective heat transfer coefficient and friction factor in single/two-phase roughened rectangular microchannels at low Reynolds numbers, showing significant impact of roughened ribs on heat transfer enhancement, especially in flow boiling conditions.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Jun Yu, Lin Su, Kang Li, Mingkang Liu, Hua Zhang
Summary: The study investigates a parallel flow microchannel outside heat exchanger through experiments and numerical simulations, finding that increasing inlet pressure and airflow result in higher heat transfer rates. A modified Nusselt number correlation model is proposed for predicting heat exchanger characteristics, showing good agreement between modeling and experimental results.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Kazuhito Dejima, Osamu Nakabeppu
Summary: Understanding the correlation between flow and heat transfer in an engine was the objective of this study. Local instantaneous heat flux and advection speed were measured, and Nusselt and Reynolds numbers were calculated based on the measurements. It was found that both models showed exponential variation of the ensemble-averaged Nusselt numbers as a function of the ensemble-averaged Reynolds numbers, and correlation equations could be derived. The penetration-depth model reproduced the experimental values more accurately.
INTERNATIONAL JOURNAL OF ENGINE RESEARCH
(2023)
Article
Mechanics
Sai Peng, Tao Huang, Taiba Kouser, Xiao-Ru Zhuang, Yong-Liang Xiong, Peng Yu
Summary: Viscoelasticity weakens the asymmetry of the laminar shedding flow behind a blunt body in a free domain. This finding was confirmed through the study of four types of unsteady viscoelastic flows with asymmetric flow configurations. At high Weissenberg number, an arc-shaped region with high elastic stress, similar to a shock wave, forms in the frontal area of the blunt body.
Article
Thermodynamics
M. Basit Shafiq, Usman Allauddin, Mumtaz A. Qaisrani, Tauseef-ur-Rehman, Naveed Ahmed, M. Usman Mushtaq, Hafiz Muhammad Ali
Summary: This study investigated the improvement in thermal performance of heat exchangers through the combination of two passive techniques, nanofluids and coiled tubes. Numerical simulations showed that using nanofluids can increase the Nusselt number, especially in shell and helical coil tube heat exchangers.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Thermodynamics
Song Xin, Wenhao Wang, Cong Zhang, Chen Li, Hao Li, Wenyu Yang
Summary: This study investigated the rock-airflow heat-transfer mechanism in headings with a forced auxiliary ventilation system, focusing on factors such as heading cross-sectional shape, roughness on rock surfaces, and Reynolds number of airflow. Results showed that Reynolds number had the highest impact on convective heat-transfer coefficients and wall temperatures, while heading cross-sectional shape had the most significant influence on longitudinal lengths of heat-transfer regions.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Thermodynamics
Subhanker Paul, Maria Fernandino, Carlos A. Dorao
Summary: During convective boiling heat transfer, the dominant role of vapor Reynolds number has been overlooked, while the enhancement factor to the liquid Reynolds number does not appropriately correlate the heat transfer coefficient. Most proposed enhancement factors can be rewritten in terms of the explicit contribution of the Re-v.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Chemical
Ruibai Qi, Fangfang Chen, Linjie Xu, Jiawen Yu, Xiaoping Chen
Summary: The flow and heat transfer characteristics in micro-tube are important research fields. In this study, the influence of Reynolds number on the overall characteristics of flow and heat transfer was investigated using a micro-tube with dimples. Results showed that the dimples promoted flow instability and improved heat transfer efficiency. The fully developed position of flow remained unchanged regardless of Reynolds number. Friction factor and heat transfer factor decreased with increasing Reynolds number.
Article
Engineering, Aerospace
Wen-Chung Wu, Ankit Kumar
Summary: In this study, the flow characteristics of nanofluid over a backward facing step at low Reynolds number were numerically investigated, and the heat transfer was analyzed. The results showed that the use of nanofluid increased the heat transfer coefficient and Nusselt number, while decreasing the coefficient of skin friction and outlet temperature.
Article
Thermodynamics
Zengkun Zhan, Lixia Chen, Hongna Zhang, Chuandong Lin, Sining Li, Xiaobin Li, Fengchen Li
Summary: This research proposes a new technique for heat transfer enhancement using viscoelastic fluid pulsating laminar flow (VPL flow). Numerical studies and flow performance analysis show that VPL flow significantly improves the overall heat transfer performance, with optimal enhancement achieved at pulsation frequencies close to the characteristic frequency of the viscoelastic fluid flow.
APPLIED THERMAL ENGINEERING
(2022)
Article
Physics, Fluids & Plasmas
Wentao Dai, Huiying Wu, Zhenyu Liu, Shengyuan Zhang
Summary: An improved curved-boundary scheme with second-order velocity slip condition is proposed for the simulation of microgas flow. The scheme utilizes the IBB and ECE methods to accurately capture gas slip velocity and eliminate the influence of fictitious slip velocity. Numerical results show that the proposed scheme improves computational accuracy and provides a precise scheme for curved boundary with second-order slip condition.
Article
Materials Science, Ceramics
Van-Huy Nguyen, Mehdi Shahedi Asl, Seyed Ali Delbari, Quyet Van Le, Abbas Sabahi Namini, Joo Hwan Cha, Sea-Hoon Lee, Ho Won Jang, Mohsen Mohammadi, Mohammadreza Shokouhimehr
Summary: The addition of SiC significantly enhanced the sintering behavior of the ZrB2-hBN composite, leading to near fully dense material. The role of SiC in oxide removal was found to be the chief cause in improving the sinterability of the ZrB2-SiC-hBN sample.
CERAMICS INTERNATIONAL
(2021)
Article
Materials Science, Ceramics
Elaheh Ranjbarpour Niari, Mohammad Vajdi, Milad Sakkaki, Shahla Azizi, Farhad Sadegh Moghanlou, Mehdi Shahedi Asl
Summary: Spark plasma sintering is an interesting manufacturing method that benefits from electric current heating. In this study, the sintering process of hafnium diboride ceramics was simulated using the finite element method and COMSOL Multiphysics software. The results showed the required temperature for sintering and the distribution of electric current in the system.
INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
(2022)
Article
Chemistry, Physical
Sheida Haji Amiri, Mahdi Ghassemi Kakroudi, Nasser Pourmohammadie Vafa, Mehdi Shahedi Asl
Summary: Fully-dense Ti3SiC2-SiC composites were synthesized in-situ and sintered through a reactive hot-pressing process using TiC and Si powders with different molar ratios. The mechanical properties of the composites were investigated, and it was found that the morphology of the in-situ synthesized SiC particles and the presence of SiC and residual TiC phase significantly influenced the performance of the composites.
Article
Materials Science, Multidisciplinary
Mehran Jaberi Zamharir, Mohammad Zakeri, Mansour Razavi, Mehdi Shahedi Asl
Summary: In this study, ZrB2-SiC-Si-based ceramic composites with WC and MoSi2 additives were fabricated using the SPS method, and their densification behavior was investigated by phase and microstructural studies. The additives reacted with surface oxide impurities of the main raw materials during the SPS process, forming oxide liquid phases and new phases such as MoB, ZrC, and WB, which contributed to the densification of the composites. The sample doped with 2.5 vol% WC and 2.5 vol% MoSi2 showed the highest relative density of about 99%, indicating the effectiveness of the SPS technology in achieving homogeneous and dense parts.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Mehdi Shahedi Asl, Abbas Sabahi Namini, Seyed Ali Delbari, Zohre Ahmadi, Mohammad Farvizi, Dokyoon Kim, Mohammadreza Shokouhimehr
Summary: The addition of carbon fiber and SiC whiskers resulted in a near fully dense ZrB2 composite, with the formation of new SiC and graphite phases reducing the presence of whisker/fiber additives in the microstructure. The synergistic effect between SiC whiskers and carbon fiber also led to the presence of many dislocations originating from plastic deformation during the SPS process and thermal expansion coefficient mismatch between adjacent phases.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
K. Deenadayalan, Vela Murali, A. Elayaperumal, A. Satheesh Kumar, S. Arulvel, Mehdi Shahedi Asl
Summary: The effect of different weight percentages of tungsten carbide on the properties of nickel-chromium alloy coatings was investigated. The heat-treated and laser re-melted coatings exhibited higher hardness and more crystalline phases compared to the as-welded coatings. The correlation between the phase structures, microstructural evolution, and friction-wear behavior among the different coatings was extensively discussed.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Microscopy
Zohre Ahmadi, Mehdi Shahedi Asl, Mohammad Zakeri, Mohammad Farvizi
Summary: This study investigated the mechanical properties and sintering behavior of additive-free and TiN-doped ZrB2 ceramics. TiN addition was found to improve the densification and mechanical properties of the ceramics.
Review
Energy & Fuels
Mehdi Shahedi Asl, Raha Hadi, Laleh Salehghadimi, Amin Goljanian Tabrizi, Sana Farhoudian, Aziz Babapoor, Majid Pahlevani
Summary: Flexible solid-state supercapacitors have the potential to revolutionize the field of wearable electronics due to their high energy density and flexibility. However, there are still challenges to overcome in terms of production, cost, and industry standards.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Chemistry, Physical
Zohre Ahmadi, Mehdi Shahedi Asl, Mohammad Zakeri, Mohammad Farvizi
Summary: In this study, the influence of TiN addition on ZrB2-SiC composite was investigated. The addition of TiN increased the porosity content, resulting in a decrease in flexural strength but an increase in indentation fracture toughness and Vickers hardness.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Mehdi Shahedi Asl, Zohre Ahmadi, Farhad Sadegh Moghanlou, Mohammad Vajdi, Mohammadreza Shokouhimehr
Summary: This investigation examines the microstructure and mechanical properties of TiB2-SiC-graphene ceramics. The results show that the system is unreactive, preventing the in-situ nucleation of B4C and TiC phases. While the presence of TiO2 and B2O3 impurities is reduced with the addition of graphene nano-platelets (GNPs), SiO2 is confirmed to be present in the final microstructure. The TiB2 phase exhibits significantly higher hardness and Young modulus compared to the SiC phase.
MATERIALS CHARACTERIZATION
(2022)
Article
Chemistry, Physical
Elham Ahounbar, Ahmad Bahmani, Behzad Nayebi, Mehdi Shahedi Asl, Seyed Mohammad Mousavi Khoei, Fateme Asl Zaeim
Summary: In this study, MgO-based ceramic layers were synthesized on a novel Mg-based substrate via plasma electrolytic oxidation (PEO). The effects of electrolyte composition on the morphology of the coatings were investigated. It was found that the coatings prepared using silicate-based electrolyte exhibited morphological inhomogeneity, while phosphate-based electrolytes improved the thickness and porosity of the coatings. The addition of Ca2+ ions in the modified phosphate-based electrolyte resulted in homogenous thickness distribution and eliminated heterogeneities in the coatings.
SURFACES AND INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Kourosh Vaferi, Mohammad Vajdi, Sanam Nekahi, Sahar Nekahi, Farhad Sadegh Moghanlou, Shahla Azizi, Mehdi Shahedi Asl
Summary: The effect of applied heat fluxes and geometric parameters on the thermal resistance and cooling capacity of microchannel heat sinks is examined. It is found that changing the rib width can significantly decrease the overall thermal resistance and improve the cooling capacity of the heat sink.
MICROSYSTEM TECHNOLOGIES-MICRO-AND NANOSYSTEMS-INFORMATION STORAGE AND PROCESSING SYSTEMS
(2023)
Article
Physics, Multidisciplinary
Kourosh Vaferi, Mohammad Vajdi, Amir Shadian, Hamed Ahadnejad, Farhad Sadegh Moghanlou, Hossein Nami, Haleh Jafarzadeh
Summary: The Tesla valve is a non-moving check valve that controls fluid flow without external power. Its unique geometry causes more pressure drop in the reverse direction than in the forward direction. This study investigated a Tesla valve with unconventional geometry through numerical analysis, and used prediction models to optimize its performance in heat transfer applications.
Article
Multidisciplinary Sciences
Kourosh Vaferi, Mohammad Vajdi, Sahar Nekahi, Amir Heydari, Farhad Sadegh Moghanlou, Hossein Nami, Haleh Jafarzadeh
Summary: This research aims to optimize heat transfer and pressure drop in a bionic fractal heat sink using artificial neural network and response surface methodology. The results show that both models can accurately predict heat transfer and pressure drop, and determine the optimal design parameters. Additionally, testing different materials reveals that reducing thermal conductivity increases thermal resistance and decreases overall performance of the heat sink.
