Repetitive acoustic streaming patterns in sinusoidal shaped microchannels

TL;DR

This paper investigates how sinusoidal boundary shapes in microchannels influence acoustic streaming patterns, revealing repetitive patterns not possible in flat geometries and proposing formulas to predict these effects for improved microfluidic control.

Contribution

It introduces the study of sinusoidal boundary effects on acoustic streaming and provides predictive formulas for pattern formation, advancing microfluidic design capabilities.

Findings

Repetitive acoustic streaming patterns occur in sinusoidal microchannels.

Such patterns are unachievable in flat rectangular geometries.

Formulas are proposed to predict streaming patterns based on geometry.

Abstract

Geometry of the fluid container plays a key role in the shape of acoustic streaming patterns. Inadvertent vortices can be troublesome in some cases, but if treated properly, the problem turns into a very useful parameter in acoustic tweezing or micromixing applications. In this paper, the effects of sinusoidal boundaries of a microchannel on acoustic streaming patterns are studied. Results show that while top and bottom sinusoidal walls are vertically actuated at the resonance frequency of basic hypothetical rectangular microchannel, some repetitive acoustic streaming patterns are recognized in classifiable cases. Such patterns can never be produced in rectangular geometry with flat boundaries. Relations between geometrical parameters and emerging acoustic streaming patterns lead us to propose formulas in order to predict more cases. Such results and formulations were not trivial at a glance.