Inviscid versus viscous instability mechanism of an air–water mixing layer

Abstract

We study how confinement affects the viscous spatiotemporal instability of a two-phase mixing layer. We show that the absolute instability triggered by the inclusion of finite liquid and gas thicknesses leads to a good prediction of experimental data. In addition, this new mechanism provides a justification for the relevance of both simplified inviscid scaling laws and more sophisticated viscous approaches.