ANISOTROPIC EDDY VISCOSITY A BENCHMARK CASE STUDY IN AN IDEALISED TIDAL ESTUARY

Resumen

Numerical schemes for solving the full shallow water equations require a turbulence closure model to represent the momentum diffusion caused by turbulence that the velocity fields do not explicitly capture. Typical models include Smagorinsky, depth-U*, Prandlt, and k-epsilon. All of these models predict isotropic eddy viscosity – i.e. the diffusion of momentum acts equally in all directions. However, it is known that when modelling saline transport within an estuary with a 2D scheme, mass dispersion is present in the longitudinal direction due to the depth velocity profile. In a 2D numerical scheme, should diffusion of momentum also be applied anisotropically? In this paper we present a benchmark case study between laboratory measured velocity results and those from numerical simulations using TUFLOW.