  Experimental and numerical investigations are performed to provide an
assessment of the transport behavior of an ultrasonic oscillatory two-phase
flow in a microchannel. The work is inspired by the flow observed in an
innovative ultrasonic fabric drying device using a piezoelectric bimorph
transducer with microchannels, where a water-air two-phase flow is transported
by harmonically oscillating microchannels. The flow exhibits highly unsteady
behavior as the water and air interact with each other during the vibration
cycles, making it significantly different from the well-studied steady flow in
microchannels. The computational fluid dynamics (CFD) modeling is realized by
combing the turbulence Reynolds-averaged Navier-Stokes (RANS) k-${\omega}$
model with the phase-field method to resolve the dynamics of the two-phase
flow. The numerical results are qualitatively validated by the experiment.
Through parametric studies, we specifically examined the effects of vibration
conditions (i.e., frequency and amplitude), microchannel taper angle, and wall
surface contact angle (i.e., wettability) on the flow rate through the
microchannel. The results will advance the potential applications where
oscillatory or general unsteady microchannel two-phase flows may be present.
