Numerical investigation of the thermal-hydraulic performance of liquid-cooled oblique-cut-fin microchannel heat sink configurations

Abstract Oblique-cut-fin microchannels are promising for high heat-flux thermal management due to their potential for enhanced fluid mixing and compact geometry. This study investigates eight configurations, classified as symmetric (SC) and periodic (PC) at 30° and 60° oblique angles, using conjugate heat transfer simulations. A physics-based Performance Index ( PI ) is employed to quantify the combined effects of convective heat transfer intensity, wetted area, and hydraulic penalty. Flow physics are further elucidated to understand flow features responsible for performance change. Results show that nearly all oblique-cut configurations outperform the straight-fin baseline over the investigated Reynolds number ( Re ) range. Among them, PC_3_30° provides the best overall thermal-hydraulic performance, with PI values ranging from 1.30 to 1.54. This configuration increases the convective heat transfer coefficient by up to 40% while reducing the pressure drop by up to 18%, despite having 5% less wetted area than the baseline. By contrast, PC_Base_30° produces the greatest convective heat transfer enhancement, with an average increase of approximately 66%, but incurs an average hydraulic penalty of approximately 55%, thereby limiting its overall performance. Flow visualization results reveal that the superior performance of PC_3_30° arises from slot-confined vortices and a vortex-cushioning effect that enhance heat transfer while moderating wall shear. In PC_Base_30°, stronger cross-flow and boundary layer disruption intensify heat transfer but substantially increase the pressure drop. These findings demonstrate that optimal oblique-cut-fin designs require a careful balance among convective enhancement, wetted area, and hydraulic expenditure, and provide design guidance for subsequent multivariable optimization of microchannel heat sinks.