Numerical Investigations Into the Mechanisms of Microbubble Drag Reduction

Abstract

Computational results of an initial attempt to model the phenomenon of skin-friction reduction by microbubble injection are presented. A well-tested boundary-layer code employing a simple mixing length model for the turbulence is used. The action of the bubbles is simulated by allowing the viscosity and density to vary locally as a function of a prescribed bubble concentration profile. Parametric studies of bubble location in the boundary layer, peak concentration and mixture viscosity model are performed. The order of magnitude and trends of the experimental skin-friction reduction are reproduced quite well by this simple model.