Development of a Phase-Field Method for Phase Change Simulations Using a Conservative Allen-Cahn Equation

Abstract

\n To simulate heterogeneous bubbly flows, a hybrid method has been developed in several studies by combining the two-fluid model and the interface tracking method. Since this original hybrid method is based on the one-pressure modeling which is a common approach for the two-fluid model, unphysical flow would occur in the flow where the surface tension is dominant. To resolve this inherent weakness of one-pressure modeling, we proposed a new formulation of the hybrid method in this study. The proposed hybrid method includes no pressure term in the dispersed phase because we regarded the dispersed phase as a group of discrete particles. We employed the phase-field method as the interface-tracking method to increase extendability to the thermal fluid model in the future. The proposed hybrid method was validated in several numerical simulations. Using the static bubble problem, we confirmed that in the proposed hybrid method simulation there is no unphysical flow which is observed in the original hybrid method. In the bubble plume problem, we compared the bubble plume behavior and the time-averaged void fraction of the simulation results with those of previously reported experiments, and found good agreement between them. From these validations, we confirmed that the proposed hybrid method was applicable to heterogeneous bubbly flow simulation and it avoided the weakness which the original hybrid method has.