Ultrasound-Driven Fluid Motion - Modelling Approach

Abstract

Fluid motion induced by ultrasound is an effect that arises from the attenuation of sound waves in a fluid. This phenomenon allows for a series of applications in industry. To achieve a significant effect in practice, high-intensity acoustics is required, which can solely be realized using the characteristics of ultrasound. Its high-frequency behaviour on one side is confronted with the nearly steady-state nature of the fluid flow on the other side. The present study proposes a numerical modelling approach to further investigate and identify development potential. The coupling of acoustics and fluid flow poses a challenging multiphysics problem, its treatment requires an appropriate handling of transient quantities on the different frequency scales. Basically the force triggering a low frequency fluid flow arises based on the time average of quantities varying on a high frequency scale. The analysis includes an estimation of acting terms by dimensionless relations as well as a verification by means of a simplified test-case. The concept presented is numerically stable and appropiate. It can be adapted to related applications involving sound-driven fluid motion.