Investigation of flow and heat transfer characteristics in microchannel with high-frequency ultrasound

Microchannel heat sinks (MCHSs) are one of the most effective heat sinks and are widely used in microelectronic devices. In this work, the flow characteristic and heat transfer synergistic analysis were presented and investigated in a microchannel with adding 2.24 MHz high-frequency ultrasound. The results indicated that acoustic streaming was the main factor affecting the flow pattern and heat transfer performance in the microchannel. At low flow rates, the acoustic streaming had a great impact on heat transfer process in the microchannel. But at large Reynolds numbers, the fluid had much stronger resistance due to the acoustic streaming disturbance. Consequently, the enhanced influence of acoustic streaming was gradually weakened. When the Reynolds number is 16.77, the addition of ultrasound increases the Nusselt number by nearly 5.2 times. From transient analysis, it can be concluded that the ultrasound-induced acoustic streaming effect improves the heat transfer between the fluid and the wall, as well as between the fluids in different layers, which consequently improves the heat transfer performance in the microchannel. The work provides the reference for revealing the impacts of high-frequency ultrasound-induced acoustic streaming effect on the flow and heat transfer characteristics in microchannels.