Capillary flow and heat transfer in passive liquid driven microchannels with random surface roughness

With the increasing demand for green computing, capillary microchannel heat sinks have attracted wide attention in the field of thermal management. The surface roughness is unavoidable due to manufacturing tolerance. In this study, to explore the effect of surface roughness on capillary flow and convective heat transfer in the capillary microchannel, a new random rough model is applied to construct rough surfaces. The results show that the rough surface has an adverse effect on the capillary flow. The shape of the meniscus and viscosity dissipation rate fluctuate randomly disturbed by rough surfaces, resulting in fluctuations in flow velocity in rough microchannels. Rougher surfaces perturb liquid flow more violently and widely. A rougher surface causes a greater average viscosity dissipation rate, impeding liquid flow. When the roughness is more than 1.93%, a rough surface effectively enhances the heat transfer efficiency of the capillary microchannel with low Reynolds number flow. Additionally, although the flow mass flux of the fluid involved in the convective heat transfer process reduces, the total heat absorption of all liquid is still enhanced due to the increased heat transfer efficiency and heat transfer area, with the increasing roughness. The simulation results are expected to provide suggestions for roughness control in capillary microchannel manufacturing.