Large-Scale Simulations of Bubble-Induced Convection in a Liquid Layer

Abstract
The flow pattern induced by a swarm of bubbles rising in a liquid layer is studied numerically. The fluid motion is described by spatially filtered Navier-Stokes equations forced by the presence of the bubbles. When the volume fraction and the residence time of the bubbles increase, a Rayleigh-Taylor-type instability develops. After transient stages, the flow reaches an equilibrium state made of counterrotating cellular structures. The simulations suggest that no wavelength selection mechanism exists in the present situation, making a striking difference with thermal convection.