Author(s): Peggy Zinke; Nils Reidar B. Olsen

Linked Author(s): Nils Reidar B. Olsen, Peggy Zinke

Keywords: Sediment; Vegetation; CFD modeling

Abstract: A CFD model was tested against an experimental data set to examine the influence of emergent vegetation on sediment transport. The model solved the Reynolds-averaged NavierStokes equations for the water flow and the convection-diffusion equation for suspended sediments. A 3D grid was used together with the finite-volume-method and the k-ε-model for the turbulence. The numerical model was set up in similarity to published laboratory flume experiments with a partly vegetated open channel where the vegetation stems in the laboratory were represented by rigid cylindrical rods in a staggered arrangement. In the numerical model the drag force on the vegetation was included as a sink term in the Navier-Stokes equations. The change of turbulence characteristics due to vegetation was also taken into account, testing dragrelated source terms in the k- and ε-equations. The impact of re-suspension of sediments in the clear channel section was found to be as important as the use of the source terms for turbulence. With both processes included, a reasonable agreement between computation results and measurement data could be obtained. However, there are uncertainties caused by the interaction processes between open channel and vegetated flow zone.

DOI:

Year: 2007