Multiscale Modelling of Bubbly Systems Using Wavelet-Based Mesh Adaptation

Since typical industrial-scale reactors may contain many millions of bubbles, the extension of direct free-surface modelling techniques to resolve every bubble in the vessel would require far more computational power than will be available. A more immediate solution is to couple macro-scale reactor models to micro-scale models of individual bubbles and collections of a small number of bubbles. In this paper, a micro-scale modelling technique was presented and tested on the situation of a single rising bubble. The micro-scale model was based on the Volume-of-Fluid (VOF) technique combined with a dynamic mesh adaptation based on wavelet analysis to ensure a sufficient resolution at the gas-liquid interfaces. The method was based on a multi-block parallel scheme with mesh adaptivity facilitated by wavelet analysis embedded into a commercial CFD package CFX. Examples of the performance of the scheme for a bubble rising problem are given.