Ultrasonic oscillation is an efficient solution for process intensification in microreactors but with complex mechanisms. This study presents a three-dimensional simulation of Taylor flow in a square microchannel under ultrasonic oscillation. The temporal/spatial variation of the pressure and the velocity field around the bubble was investigated. Due to the pressure pulsation parallel to the oscillation direction, the non-inertial cavitation of the bubble could be induced leading to the sub-harmonic bubble surface wave. The pressure threshold for the onset of the surface wave was predicted based on the parametric resonance theory. Owing to the surface wave, a periodic oscillation of the flow field could be found and quantified both in the liquid slug and at the liquid film of the channel corner. The oscillation frequency and intensity of the flow field were determined by the Fourier analysis, then the intensification mechanism for mass transfer/mixing in ultrasonic microreactors could be clarified.

超声波振荡是微反应器中过程强化的有效解决方案，但机制复杂。这项研究提出了超声振动下方形微通道中泰勒流动的三维模拟。研究了气泡周围压力和速度场的时空变化。由于平行于振荡方向的压力脉动，会引起气泡的非惯性空化，从而导致次谐波气泡表面波。基于参数共振理论预测了表面波开始的压力阈值。由于表面波，在液塞和通道角的液膜中都可以发现并量化流场的周期性振荡。