A Front Tracking Method for Computational Modeling of Temperature and Species Gradient Based Phase Change

A front tracking method is developed to simulate the liquid-gas phase change phenomenon during vaporization/evaporation process. One eld formulation of the governing ow, energy and species equations are solved on an Eulerian grid with suitable jump conditions. Both phases are assumed to be incompressible; however, the divergence-free velocity eld condition is modi ed to account for the phase change/mass transfer at the interface. Interface/front separates the phases and is composed of connected marker points that are tracked explicitly. Temperature gradient based phase change model calculates the heat source/sink at the interface by applying the energy conservation principle. For the species gradient driven phase change model, the Clausius-Clapeyron relation is used to nd vapor mass fraction at the interface, which is subsequently used to nd the mass ux and heat ux across interface. The implementation is validated against standard test cases such as 1D Stefan problem and the evaporation of a 2D static droplet. The non-dimensional evaporation mass ux across the interface is validated against an analytical model, assuming the interface temperature constant throughout the evaporation process. For a water droplet evaporating in air, the numerical results of wet bulb temperatures are compared with the psychrometric chart values and a good agreement is observed. Finally, 2D planar moving and deforming droplets are made to evaporate for di erent Eotvos (Eo) and Morton (Mo) Numbers. The implementation is grid convergent and mass is globally conserved for all the studied cases. The next step will be to incorporate chemical reactions into the present computational method using nite-rate chemical kinetic models.