3D Direct Numerical Simulation of Air Bubbles in Water at High Reynolds Number

Abstract

This article presents direct numerical simulations of single air bubbles and bubble pairs in water (with log Mo = −10.6) with a highly parallelized code based on the Volume Of Fluid method (VOF). Systematical simulations of terminal velocity of single bubbles with a diameter ranging from 0.5–15 mm (ReB = 200–3750) show good agreement with experimental data from Clift et al. Bubbles with a diameter of 8 mm show strong realistic surface deformations. Initial white noise has been added to all simulations to create realistic starting conditions. Rise paths of the bubbles depend strongly on the boundary conditions and the wall distance. Small wall distances reduce the path radii of the bubbles leading to an increased wake shedding frequency. For bubble pairs with wobbling surfaces the phenomenon of shedding of vortices from the edges of the bubbles is observed.