Flexible hydrostatic reconstruction in Riemannproblem
There exist different hydrostatic reconstructions for modelling shallow water flows over uneven terrain. The reconstruction is applied to obtain a state on the left/right side of an edge to be able to compute the flow with a Riemann Solver.
In DuMux, the hydrostatic reconstruction of Audusse et al. is implemented, which is a good choice for modelling flow in rivers. However, the method has it limitations for flows with small water depths and large slope variations (e.g. rainfall-runoff modelling). A rainfall-runoff benchmark showed that the results can be strongly improved by using the reconstruction method of Chen and Noelle, but this method can be problematic if the slope gradient gets equal to the water height.
Actually the hydrostatic reconstruction is hard-wired in the riemannProblem
. The structure of the code is a bit complex/messy since ShallowWaterFlux
calls the riemannProblem
in which the reconstruction is performed before the exactRiemann
(exact Riemann Solver) is called.
It would be nice to provide different kind of reconstructions.
@utz what do you think?