An Approach to Couple Shallow Water and Navier-Stokes Suited for Upstream-Travelling Shock Waves Based on OpenFOAM Framework - shallowInterfoam

This paper describes an approach to an improved treatment of an upstream-travelling hydraulic jump within a 2D-3D coupling framework. The coupling solver shallowInterFoam combines the 2D Shallow Water solver shallowFoam with the 3D Navier-Stokes solver interFoam. These solvers are available as an Open Source software in the OpenFOAM framework (Mintgen and Manhart, 2017). The original coupling algorithm as proposed by Mintgen and Manhart (2017) uses combinations of Dirichlet-Neumann boundary conditions at the 2D-3D interface depending on the flow situations. This coupling algorithm performs well in most application scenarios. However, an upstream-travelling shock wave is unable to cross the 2D-3D interface due to the direction of the characteristics in supercritical flows. Therefore, a different approach is proposed here. It overlaps the domains which allows Dirichlet conditions for the downstream boundary, even in supercritical flows. A series of numerical tests with an upstream-travelling hydraulic jump establish a proof-of-concept for the proposed overlapping method.