Thermo-hydraulic evaluation of perforated hourglass pin-fin designs in micro pin fin heat sinks

Efficient thermal management is crucial for next-generation microelectronic systems operating under increasingly high heat flux conditions. This work presents a comprehensive numerical study to evaluate the thermo-hydraulic performance of advanced micro pin-fin heat sink configurations, including innovative hourglass-shaped and hybrid geometries, under laminar forced convection. The governing equations for mass, momentum, and energy are solved using the finite volume method (FVM) implemented in ANSYS Fluent, with all models validated against experimental data from the literature. The effects of fin shape, fin arrangement, and Reynolds number on heat transfer enhancement, pressure drop, temperature uniformity, and overall performance are systematically analyzed. Results indicate that hourglass configurations significantly promote fluid mixing, disrupt boundary layers more effectively, and increase the heat transfer coefficient by up to 67% compared to simple geometries. Although there is a moderate increase in pressure drop, the hourglass circular design offers the best overall performance, demonstrating superior thermal resistance reduction and more uniform temperature distribution. This study illustrates the delicate balance between geometric modifications and hydraulic penalties and emphasizes the importance of an optimized pin-fin topology for compact, high-heat-flux cooling solutions. Overall, this work provides new insights into the design of micro pin-fin heat sinks and establishes a detailed thermo-hydraulic performance benchmark for emerging micro-scale cooling technologies.