Interface Tracking Simulation of Mass Transfer from a Dissolving Bubble

Abstract

An interface tracking method for predicting bubble dissolution process is proposed. A non-diffusive scheme for advecting species concentrations is adopted to accurately compute the volume change due to mass transfer. The applicability of the proposed method is examined through several benchmark tests, i.e. mass transfer from stationary bubbles and that from free rising bubbles. Dissolution of single carbon dioxide bubbles rising through a vertical pipe filled with water is also simulated to examine its applicability to high bubble Reynolds number and high Schmidt number conditions. The bubble initially consists of carbon dioxide only, whereas nitrogen and oxygen are dissolved in water. The volume change due to dissolution of carbon dioxide from the bubble and evaporation of nitrogen and oxygen from water are also accounted for. A high spatial resolution is used in this simulation to capture a thin concentration boundary layer in the vicinity of the bubble surface. As a result the following conclusions are obtained: (1) the proposed two-variable method yields no artificial diffusion of species concentrations through the interface and well conserves the species moles, (2) the method gives accurate predictions for the concentration profiles about the stationary dissolving bubbles, (3) the mass transfer rate from bubbles at intermediate Reynolds numbers and a low Schmidt number is well predicted, and (4) the method gives good predictions for the mass transfer from the high Schmidt and high Reynolds number bubbles containing multiple gaseous species and for the volume change due to the mass transfer, provided that the spatial resolution is high enough to capture thin concentration boundary layers.