A discontinuous Galerkin finite element model for morphological evolution in shallow flows

TASSI PA; RHEBERGEN S; VIONNET CA; BOKHOVE O.

Enschede, The Netherlands

Simposio; RCEM 2007 - 5th IAHR Symposium on River, Coastal and Estuarine Morphodynamics; 2007

IAHR -Tthe International Association of Hydraulic Engineering and Research & University of Twente (The Netherlands)

The accurate representation of morphological processes and the ability to propagate changes in the riverbed over a wide range of space and time scales make the design and implementation of the appropriate numerical scheme challenging. In particular, requirements of accuracy and stability for medium and long term simulations are difficult to meet. In this work, simulations of a discontinuous Galerkin finite element method (DGFEM) for sediment transport and bed evolution equations are presented. Numerical morphological models involve a coupling between a hydrodynamic flow solver which acts as a driving force and a bed evolution model which accounts for sediment flux and bathymetry changes. The resulting numerical scheme is verified by comparing simulations versus (semi–) analytical solutions. These include the evolution of an initially symmetric, isolated bedform; the formation and propagation of a step in a straight channel due to a sudden overload of sediment discharge; and, the morphological evolution of an initially flat bed in a converging channel. Finally, a comparison is made between the numerical model and field data of a trench excavated in the main channel of the Paraná River (Argentina).