Mathilde Tavares (∂'Alembert)

Numerical modelling of two-phase flows interacting with arbitrary solid surfaces

Multiphase flows in complex geometries are present in many environmental contexts and industrial applications, from raindrops impacting on leaves and plants, to droplet deposition on fog harvestingstructures, from multiphase fluid-structure interactions in power plants, to 3D printing. In these situations, three different phases are at least concerned: two fluids, a gas and a liquid in general; and a solid. We present a hybrid Volume of Fluid/embedded boundary method allowing to model two-phase flows in presence of solids with arbitrary shapes. The method relies on the coupling of existing methods: a geometric Volume of fluid (VOF) method to tackle the two-phase flow and an embedded boundary method to sharply resolve arbitrary solid geometries. Coupling these approaches consistently is not trivial and we present in detail a quad/octree spatial discretization for solving the corresponding partial differential equations. We propose here a robust implementation of the boundary conditions at the solid liquid interface (Navier slip BC) and also at the triple line (solid, liquid, gas intersection) with the challenging contact angle modelling. The robustness and accuracy of the developed method is validated on different test cases and an application to phase change with the droplet solidification is proposed.