Multiscale Modeling of the Evaporation Process

Two-phase flows play an important role in numerous natural phenomena and industrial applications. Especially phase transition phenomena and topological changes are challenging for numerical methods, since the macroscopic behavior is influenced by microscopic effects at the phase boundary. In this work a novel multi-scale model for compressible two-phase flows with phase transition is proposed. A sharp interface level-set ghost-fluid method is used to combine the macroscopic Godunov-Peshkov-Romenski flow model with a microscopic model of the phase boundary via a two-phase Riemann solver. This allows the simulation of evaporating fluids. The approach is validated against molecular dynamics simulations and compared with experimental results for evaporating Propane, Butane and n-Dodecane. In addition the level-set ghost-fluid method is extended to allow topological changes. Therefore, the level-set transport equation is discretized with a path-conservative discontinuous Galerkin scheme, which is stabilized with finite volume sub-cells. Additional modifications allow the correct transport of approaching phase boundaries and thus the simulation of topological changes. The capabilities of the scheme are demonstrated by comparing simulation results for a drop-drop collision with experimental findings.