Bio-inspired fish-like micropins for enhancing the thermo-hydraulic performance of wavy microchannel heat sinks for IGBT cooling

Efficient liquid cooling is essential for high-power insulated gate bipolar transistor (IGBT) modules in new energy vehicles. This study proposes a wavy microchannel heat sink with bio-inspired fish-like micropins (SWP-FS) to improve the heat transfer-flow resistance trade-off. Compared with streamlined micropins, the fish-like micropins are designed to preserve favorable flow guidance while promoting local flow splitting and wake disturbance. A comparative numerical study is performed using a conventional straight microchannel (TC), a wavy microchannel (SWP), and a wavy microchannel with streamlined micropins (SWP-SP) as reference configurations. Response surface methodology (RSM) is then used to optimize the micropin height H , micropin offset L , and fish-like truncation coefficient λ . The results show that the bio-inspired fish-like micropins intensify transverse and longitudinal secondary flows, promote near-wall fluid renewal, and enhance convective heat transfer. Response surface analysis identifies λ as the dominant structural parameter, with the H - λ interaction exerting the strongest coupled effect. The optimal configuration is H = 0.45 mm, L = 0.40 mm, and λ = 0.58. Compared with SWP-SP, the optimized SWP-FS configuration increases the Nusselt number Nu by 39.2%–53.4% and the Fanning friction factor f by 33.5%–96.4%, while improving the performance evaluation criterion ( PEC ) by 32.7%–45.9%. These findings clarify the thermo-hydraulic advantages of fish-like micropins over streamlined micropins and provide design guidance for high-performance liquid-cooled microchannel heat sinks for IGBT thermal management in new energy vehicles.