A Numerical Study on Heat Transfer Performance in a Straight Microchannel Heat Sink with Standing Surface Acoustic Waves

Abstract

There has been a remarkably increasing interest in applying acoustofluidics in micro-electro-mechanical systems and lab-on-a-chip systems in the past decades. This paper investigated the heat transfer performance in a straight microchannel heat sink which applies standing surface acoustic waves (SSAW) to disturb the flow. Two-dimensional numerical simulations of the SSAW-driven flow are performed by employing perturbation theory on basis of COMSOL platform. The elasticity of microchannel material is taken into account by applying the impedance boundary conditions. Parametric effects on heat transfer performance including the SSAW wavelength and the dimensions of microchannel heat sink are investigated. It is found that the introduction of SSAW can greatly enhance the overall heat transfer. Moreover, with a constant channel height, shorter SSAW wavelength and narrower microchannel are found to be more beneficial to the overall thermal performance. Keeping both the microchannel width and the SSAW wavelength unchanged, a “wide” configuration of the microchannel cross section is recommended to achieve higher heat transfer efficiency. Finally, we elucidate the underlying mechanisms of heat transfer enhancement peculiar to the excitation of SSAW in microchannel, which is attributed to the appearance of acoustic vortices and the disruption of thermal boundary layer induced by acoustic streaming.