• Shallow Water

Implicit simulations for morphodynamic Shallow Water flows are considered. The efficiency of implicit time advancing is evaluated when the Froude number is increased for 1D Shallow Water problems using the Grass model and the Meyer-Peter Muller one for the evolution of the bedload. A reduction of the maximum CFL allowable for implicit simulations has been found when increasing the Froude number, but for the most part they are still advantageous with respect to the explicit ones from the point of view of computational costs for low speeds of interaction between the bedload and the fluid. A 2D problem is then considered: implicit simulations are applied to a contracting channel in order to evaluate their convenience with respect to the explicit ones carried out in the study of reference, finding out that there is a large gain in computational costs when using implicit time advancing, even if slight differences in the evolution of the bottom profile, due to differences of the meshes and of the numerical schemes, have to be taken into account.