Bio-inspired micropillar arrays for enhanced thermal-hydraulic performance in microchannel heat sinks: A numerical and experimental study

Microchannel heat exchanger is an efficient solution for addressing the thermal management challenges posed by high power devices. Embedding solid micropillars within microchannels has proven to be an effective method for enhancing heat transfer. However, the formation of vortices behind these micropillars increases pressure drop and leads to heat accumulation inside the channels. Drawing inspiration from the streamlined body of the butterflyfish, two micropillars Type A and a modified Type B were designed, incorporating an arc-shaped "fish tail" with a slotted structure to reduce flow resistance. The thermal and hydrodynamic characteristics of this new microchannel heat exchanger were investigated through both numerical simulation and experimental study. The laser micromilling method was used to fabricate the bionic micropillars on the bottom of rectangular microchannels. The results indicate that the Nusselt number of Type A micropillars is 8.2–16.5 % higher than that of solid micropillars, with a corresponding pressure drop reduction of 7.8–16 %. Type B micropillars demonstrate a 2.7–12.5 % increase in Nusselt number and a reduction of 10.1–16.7 % in the pressure drop. Performance evaluation criterion (PEC) values for Type A range from 1.01 to 1.71, while Type B ranges from 0.99 to 1.67, highlighting excellent overall heat transfer performance. The superior performance is attributed to the secondary flow formed by bionic micropillars, promoting fluid continuity and providing sufficient momentum to overcome viscous forces along the flow direction. These findings highlight the potential of biomimetic strategies in advancing microchannel heat sink design.