Methods for multiphase flows with high density ratio

Two-phase flows with high density ratio and high shear are known to be challenging to simulate. In this work, two strategies for improving the robustness of high density ratio two-phase flow simulations are investigated. The first method, based on Rudman’s work with the volume of fluid method (Rudman 1998), aims at improving the consistency between interface and momentum transport by using the interface position to estimate the density that appears in the momentum convection fluxes. The second approach effectively decouples gas and liquid velocities by introducing two distinct vector fields coupled through the pressure Poisson equation, in the spirit of the ghost fluid method Fedkiw et al. (1999). An algorithm that reconstructs the liquid velocity in the gas and the gas velocity in the liquid is then employed, ensuring that the velocity field is continuous while allowing for discontinuous gradients at the interface. These two methods are evaluated on a droplet convection test case, and both are found to improve significantly the robustness of the simulations.