DNS analysis of turbulent mixing in two-phase flows

This study focuses on the evaporation and mixing process in turbulent two-phase flows with a direct resolution of the flow near the interface. A first approach, using a passive scalar to represent the evaporation and mixing process in a two-phase dense turbulent flow, has been developed and applied in a homogeneous isotropic turbulence over a large range of liquid volume fractions. This model is restricted to low vaporization rates, thus the interface is barely affected by the evaporation process. A statistical analysis of the vapor field is performed. Obtained results suggest that the beta PDF, frequently used in combustion modeling, are not adequate to represent the state of scalar mixing when interfaces are taken into account. tral analysis of the velocity and the scalar field is carried out simultaneously in both phases as well as in each phase separately. A procedure using the liquid volume fraction field is employed to separate the contribution of each phase. The evaporation process does not affect the spectrum shape of the scalar, but it has a direct influence on the energy level of the scalar.