DNS analysis of weakly compressible vaporizing turbulent two-phase flows
Résumé
Recent improvements in numerical methods allows researchers to perform Direct Numerical Simulations (DNS) of two phase flows with interface tracking or capturing. Taking into account phase change and describing the interface accurately is still a challenge due to the presence of discontinuities (density, velocity, viscosity …) across the interface. In this work, a two phase flows DNS including phase change with (and without) interface regression is used to study the impact of vaporization on the interface, but also its impact on the mixture fraction and scalar dissipation rate statistics in the gas phase. These quantities are of great interest to evaluate the molecular mixing efficiency and, for example, have a direct impact on combustion ignition. The numerical configuration used is a two phase flows Homogenous Isotropic Turbulence (HIT), which have been validated in previous work. Since most numerical methods dedicated to phase change are designed with a constant gas density in mind, specific numerical methods have been developed to consider the density variation in the gas phase due to the combination of the vapor production induced by vaporization and the presence of periodic boundary conditions (confinement effect).