Coupling of a discontinuous Galerkin finite element marine model with a finite difference turbulence closure model

This paper describes an online coupling between a 3D discontinuous Galerkin finite element marine model and a 1D vertical turbulence closure model based on finite differences. The coupling exploits the topology of the 3D mesh, that is formed by stacking layers of prisms in the vertical direction. A robust mapping between the finite difference grid and the finite element function space is designed, taking into account the discontinuities in the latter. The coupling is tested with two horizontally homogeneous flows and an idealised 3D estuary simulation. The results are in good agreement with those obtained with a finite difference model using the same turbulence closure, indicating that the coupling does not deteriorate the performance of the turbulence model.