Ultrasonic Oscillatory Two-phase Flow in Microchannels

TL;DR

This study investigates the complex, unsteady ultrasonic oscillatory two-phase flow in microchannels through experiments and CFD modeling, revealing how vibration parameters and surface wettability influence flow behavior.

Contribution

It introduces a combined experimental and numerical approach to analyze unsteady two-phase flow in vibrating microchannels, highlighting effects of vibration and surface properties.

Findings

Flow behavior is highly unsteady and influenced by vibration parameters.

CFD model with RANS k-ω and phase-field effectively predicts flow dynamics.

Flow rate varies with vibration frequency, amplitude, and surface wettability.

Abstract

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.