A discontinuous Galerkin method for a new class of Green-Naghdi equations on simplicial unstructured meshes
For researchers in coastal engineering and geophysical fluid dynamics, this work provides a flexible numerical framework that extends shallow water models to include dispersive effects on arbitrary meshes.
This paper introduces a discontinuous Galerkin method for a new class of Green-Naghdi equations on unstructured simplicial meshes, enabling high-order accurate simulation of free surface flows with non-hydrostatic effects. The method preserves steady states and water height positivity, and is validated through benchmarks on nonlinear wave transformations and run-up over complex topographies.
In this paper, we introduce a discontinuous Finite Element formulation on simplicial unstructured meshes for the study of free surface flows based on the fully nonlinear and weakly dispersive Green-Naghdi equations. Working with a new class of asymptotically equivalent equations, which have a simplified analytical structure, we consider a decoupling strategy: we approximate the solutions of the classical shallow water equations supplemented with a source term globally accounting for the non-hydrostatic effects and we show that this source term can be computed through the resolution of scalar elliptic second-order sub-problems. The assets of the proposed discrete formulation are: (i) the handling of arbitrary unstructured simplicial meshes, (ii) an arbitrary order of approximation in space, (iii) the exact preservation of the motionless steady states, (iv) the preservation of the water height positivity, (v) a simple way to enhance any numerical code based on the nonlinear shallow water equations. The resulting numerical model is validated through several benchmarks involving nonlinear wave transformations and run-up over complex topographies.