Numerical Study of Wavy Shape Microchannel With Disruptive Structures Based on Thermodynamics and Pumping Power

Abstract

Abstract. A three-dimensional study has been carried out to find a copper-based novel micro heatsink for efficient cooling of miniature electronic devices. The disruptive units, such as waviness, rectangular cavities, and diamond ribs, are considered to augment the heat transfer. Three different microchannels are taken as a straight channel with rectangular cavity, a wavy channel with rectangular cavity, and a wavy channel with rectangular cavity and diamond rib. Microchannels are analyzed across the Reynolds number range from 66 to 530 using water as the working fluid. The performance of heat sinks is meticulously evaluated for each configuration based on the thermal performance (TP) and entropy generation number (EGN). The higher TP reflects more heat transfer capability for the same pumping power, and the EGN is defined as the ratio of total entropy generation in a modified channel with disruptive structures to that in a smooth channel. The study explicitly explores the role of disruptive structure in creating the recirculation zone, wall shear stress, local heat transfer coefficients, vorticity, and Dean vortices in minimizing entropy generation. Moreover, the change in flow characteristic with geometrical parameters such as diamond rib's length, transverse and longitudinal rib position, and waviness amplitude of the channel is identified with improved TP and EGN. A microchannel with waviness, rectangular cavity, and diamond rib emerges as the optimal design among various channel configurations, with the highest TP being 1.44 and the lowest EGN being 0.61. This also reveals that peak local heat transfer aligns with regions of maximum wall shear stress. The addition of a diamond rib enhances the strength of the dean vortices in the downstream of the channel, whereas shifting the rib away from the cavity center in either direction leads to a reduction in TP.