Shahrood University of Technology Journal of Solid and Fluid Mechanics 2251-9475 15 5 2025 11 22 Effect of Geometric and Thermophysical Properties of Porous Medium on Thermal Performance of a Finned Microchannel Heat Sink Effect of Geometric and Thermophysical Properties of Porous Medium on Thermal Performance of a Finned Microchannel Heat Sink 443 456 3710 10.22044/jsfm.2025.15967.3953 FA Somayeh Davoodabadi Farahani Mechanical Engineering Department, Arak University of Technology, Arak, Iran Alireza Alibigieghd Arak University of Technology, Arak, Iran Journal Article 2025 03 27 This study numerically and three-dimensionally investigates the thermal performance of a microchannel heat sink integrated with a porous medium. Three different microchannel geometries—including square, circular, and finned—are considered, with conductive heat transfer modeled in the solid regions. Numerical simulations are performed using ANSYS Fluent . The Reynolds number range in this study is between 50 and 1000, representing laminar flow conditions.The effects of a newly designed porous fin, variations in microchannel geometry, heat flux distribution, porosity, Darcy number, and the ratio of solid to fluid thermal conductivity within the porous medium on the thermal performance of the microchannel heat sink are evaluated. Results indicate that the square microchannel heat sink exhibits superior thermal performance compared to other geometries. The thermal performance of the system is directly influenced by the spatial distribution of heat flux on the active surface, which plays a key role in enhancing heat transfer.<br />Furthermore, the use of porous fins improves the thermal performance of the microchannel heat sink, with the degree of enhancement depending on porous medium properties such as porosity, Darcy number, and the thermal conductivity ratio. Among these, the thermal conductivity ratio of the porous medium significantly affects system performance. Notably, employing a porous medium with porosity varying as a function of position along the flow direction (z-axis) can improve thermal performance by approximately 38%. This study clearly demonstrates that variations in porous medium characteristics, especially porosity and thermal conductivity, can have substantial impacts on the thermal performance of microchannel heat sink systems. This study numerically and three-dimensionally investigates the thermal performance of a microchannel heat sink integrated with a porous medium. Three different microchannel geometries—including square, circular, and finned—are considered, with conductive heat transfer modeled in the solid regions. Numerical simulations are performed using ANSYS Fluent . The Reynolds number range in this study is between 50 and 1000, representing laminar flow conditions.The effects of a newly designed porous fin, variations in microchannel geometry, heat flux distribution, porosity, Darcy number, and the ratio of solid to fluid thermal conductivity within the porous medium on the thermal performance of the microchannel heat sink are evaluated. Results indicate that the square microchannel heat sink exhibits superior thermal performance compared to other geometries. The thermal performance of the system is directly influenced by the spatial distribution of heat flux on the active surface, which plays a key role in enhancing heat transfer.<br />Furthermore, the use of porous fins improves the thermal performance of the microchannel heat sink, with the degree of enhancement depending on porous medium properties such as porosity, Darcy number, and the thermal conductivity ratio. Among these, the thermal conductivity ratio of the porous medium significantly affects system performance. Notably, employing a porous medium with porosity varying as a function of position along the flow direction (z-axis) can improve thermal performance by approximately 38%. This study clearly demonstrates that variations in porous medium characteristics, especially porosity and thermal conductivity, can have substantial impacts on the thermal performance of microchannel heat sink systems. https://jsfm.shahroodut.ac.ir/article_3710_80690f48d17b9a7062178732d0845690.pdf