Numerical investigation of flow and heat transfer in microchannel with square rib modified by triangular extensions

Abstract Efficient thermal management is crucial in compact electronic systems, where conventional cooling method often fail under high heat flux conditions. This study numerically investigates the fluid flow and heat transfer characteristics in a rectangular microchannel featuring square rib modified with triangular extensions oriented either upward or downward named as Forward triangular rib connected with square Rib (FTRS), backward triangular rib connected with square rib (BTRS). Three dimensional numerical investigations have been carried out for Reynolds number ranging from 4 to 800 to analyze the flow separation, recirculation, wall shear stress, pressure coefficient, heat transfer coefficient, velocity deficit and cooling uniformity index. The results reveal that orientation of rib has a significant effect on wake dynamics and thermal performance. The FTRS have a 17% higher returning velocity in the wake, resulting in a large wake and longer recirculation zones at Re equal to 300. Shear stress analysis revealed that that, a higher Re equal to 300, the FTRS yielded 44.61% reduction in maximum bottom wall shear stress and 14.14% reduction in maximum side wall shear stress, reflecting weaker velocity gradient near walls. The pressure distribution revealed maximum pressure coefficient, at the trailing edge for BTRS and at the leading edge for the FTRS. The BTRS achieved a 38.12% higher local heat transfer coefficient at Re equal to 300, confirming its superior heat-transfer performance. For both cases, the cooling uniformity index increases with increasing Re, with the BTRS consistently providing slightly higher cooling uniformity index.