Modeling 3D Rhône river plume using a higher order advection scheme

Abstract

Effects of discretization scheme on the numerical modeling of 3D Rhône River plume dynamics are investigated. A higher order scheme of total variation diminishing (TVD) type is used to discretize advection terms of both momentum and scalar equations. It is shown that this scheme widely damps the numerical diffusion and improves the representation of the dynamical and density fronts bounding the flow. It enables to accurately investigate the effects of the turbulent diffusion, which was previously masked by the numerical one. Numerical results are also compared to in situ data for two situations related to different wind conditions. For the case without wind stress, associated to supercritical values of the Richardson number, optimized turbulent parameterization allows to recover the plume spreading and thickness, although local diffusion mechanisms are not precisely described. On the other hand, for the seaward wind case, associated to subcritical values of the Richardson number, numerical results and in situ data well agree on both the surface flow and the vertical density structure.