Upscaling of Coupled Free-Flow and Porous-Medium-Flow Processes

The behavior of a coupled free-flow/porous-medium-flow system strongly depends on the pore-scale processes happening at the shared interface. Under certain conditions, drops form at this interface and affect the exchange of mass, momentum, and energy. The mutual influence of droplet-related pore-scale processes and the surrounding’s macro-scale flow behavior poses a challenge for both the conceptual and the numerical model. The aim of this work is to develop a computationally efficient model concept, which takes the processes at both scales into account. We use a lower-dimensional interface domain to embed the drop dynamics into a coupled macro-scale model. In this domain, the droplet-related processes are modeled with separate balance equations. Coupling conditions take the fluxes from and to the macro-scale flow regimes into account. First results of a simple test case show that drop formation, growth, and detachment can be represented with this multi-scale three-domain approach.