Porous-medium flow is coupled to free flow in a broad variety of medical, technical and environmental systems. Simulating the coupled flow and transport processes helps to understand e.g. evaporation dynamics from soils or some processes in fuel cells.
In a turbulent free-flow regime, a viscous sublayer evolves. As this layer is extremely small and has a crucial effect on evaporation processes, it should be resolved by a fine grid. For a flat surface, a (globally refined) graded grid can be used to capture the sublayer processes while keeping the computational effort acceptable. Here, however, the influence of surface roughness on the flow and mass exchange across the soil surface should be studied. With roughness, refining the interface region requires a locally refined grid, which is implemented in this research project.
Additionally, this work includes a first step to decouple the system, in order to, among others, have smaller subsystems and be able to use different solvers suitable for the respective subsystems. Different solvers and solution strategies suitable for solving the free-flow subsystem are implemented and compared.