A phase inversion benchmark for multiscale multiphase flows.

A series of benchmarks based on the physical situation of "phase inversion" between two incompressible liquids is presented. These benchmarks aim at progressing toward the direct numerical simulation of two-phase flows. Several CFD codes developed in French laboratories and using either Volume of Fluid or Level Set interface tracking methods are utilized to provide physical solutions of the benchmarks, convergence studies and code comparisons. Two typical configurations are retained, with integral scale Reynolds numbers of 13.700 and 433.000 respectively. The physics of the problem are probed through macroscopic quantities such as potential and kinetic energies, interfacial area, enstrophy or volume ratio of the light fluid in the top part of the cavity. In addition, scaling laws for the temporal decay of the kinetic energy are derived to check the physical relevance of the simulations. Finally the droplet size distribution is probed. Additional test problems are also reported to estimate the influence of viscous effects in the vicinity of the interface.