Acoustic streaming and its suppression in inhomogeneous fluids

TL;DR

This paper investigates how inhomogeneities in fluid density and compressibility can suppress boundary-driven acoustic streaming, combining theoretical, numerical, and experimental approaches.

Contribution

It introduces a new understanding of how non-dissipative forces in inhomogeneous fluids alter and suppress acoustic streaming flows.

Findings

Inhomogeneous fluids exhibit suppressed acoustic streaming compared to homogeneous fluids.

A non-dissipative force density stabilizes inhomogeneity configurations.

Experimental results confirm theoretical predictions of streaming suppression.

Abstract

We present a theoretical and experimental study of boundary-driven acoustic streaming in an inhomogeneous fluid with variations in density and compressibility. In a homogeneous fluid this streaming results from dissipation in the boundary layers (Rayleigh streaming). We show that in an inhomogeneous fluid, an additional non-dissipative force density acts on the fluid to stabilize particular inhomogeneity configurations, which markedly alters and even suppresses the streaming flows. Our theoretical and numerical analysis of the phenomenon is supported by ultrasound experiments performed with inhomogeneous aqueous iodixanol solutions in a glass-silicon microchip.