Modelling the mass transfer from bubbles to the liquid is challenging as the Schmidt numbers in real systems are generally in the order of 100-10.000. These high Schmidt numbers indicate that the mass transfer boundary layer is significantly thinner than the fluid dynamic boundary layer, i.e. the resolution requirement for the mass transfer is significantly higher than the resolution for the fluid dynamics. This limits the possibilities to simulate the mass transfer in realistic gas-liquid systems. The high gradients, which require the high resolution, are generally obtained in close vicinity of the gas-liquid surface. In this contribution, a method will be presented, which approximates the high gradients near the gas-liquid interface and thereby reduces the resolution requirements for the mass transfer. The method will be verified with analytical solutions in the limits of Stokes flow and potential flow. In addition, the method will be validated against high resolution simulations.

After validation and verification, the method will be used to determine the mass transfer from single bubbles in an infinite medium. The results will be compared to other numerical simulations and experimental correlations obtained from literature showing that the method is very well suited to simulate the mass transfer from bubbles in realistic gas-liquid systems.