Heat transfer augmentation in microchannels with flexible micropillars for advanced electronic cooling applications

Thermal loads in high-performance electronics are increasing, and compact cooling solutions that dissipate more heat and use less pumping power are required. However, rigid micropillar arrays are unable to adapt dynamically to satisfy these conflicting operating requirements. This study presents a two-dimensional, transient fluid-structure interaction (FSI) analysis of a microchannel heat sink with three linear elastic material with geometric nonlinearity polydimethylsiloxane (PDMS) micropillars, uniquely investigating the concurrent, coupled effects of micropillar stiffness, height, and width, rather than varying one parameter in isolation. The coupled laminar flow, heat transfer, and solid mechanics equations were solved using the Arbitrary Lagrangian-Eulerian (ALE) formulation within a moving mesh in COMSOL Multiphysics. The impacts of the Cauchy number ( C a ), the Reynolds number ( 200 ≤ R e ≤ 1000 ), and the micropillar aspect ratio ( 8 ≤ A R ≤ 13 ) on the hydrothermal and structural performance is systematically analyzed. An intermediate stiffness ( E s = 2.0 MPa , C a = 10 − 4 ) produced deflection-driven vortices yielding the maximum spatially averaged Nusselt number ( N u ═ = 43.13 ), 54% better hydrothermal performance than rigid micropillars. Increasing the Reynolds number from 200 to 1000 raised the spatially averaged Nusselt number from 29.46 to 35.42 while reducing the peak temperature from 83.6 °C to 62.0 °C. Multi-objective Pareto optimization indicated that the tall, slender micropillar structure was the optimal design for sub-85 °C operation with moderate hydraulic penalty, which has great potential for advanced electronic cooling applications.