Assessment of dynamic adaptive grids in Volume-Of-Fluid simulations of oblique drop impacts onto liquid films

Grid spacing dependence in three-dimensional numerical simulations of non-normal drop impact onto thin liquid films is assessed for different impingement angles and grid refinement levels. To describe the liquid phase dynamics, the Navier-Stokes equations are coupled to a Volume-Of-Fluid (VOF) model. Numerical simulations are performed with a modified version software OpenFOAM over a structured grid of hexaedra. Grid adaptation is carried out using an edge subdivision technique which results in non-conformal meshes. Grid convergence is assessed by monitoring integral parameters describing the dynamics of the post-impact free-surface waves. Starting from an initial grid spacing between D/8 and D/5, with D drop diameter, a refinement level of three is found to be sufficient to describe the diverse flow feature and to identify the splashing regime.