Author(s): Gergely Tihamer Torok; Sandor Baranya; Nils Ruther
Keywords: No Keywords
Abstract: In this paper we investigated the numerical analysis of river morphodynamics with nonuniform bed materials. Many uniform sediment transport models can be found in the literature. But the experiences have shown that these models are not suitable to describe non-uniform sediment transport. Moreover, laboratory and field studies suggest that the interaction between bed grains should be taken into account when describing sediment transport. Wilcock and Crowe developed a transport model for mixed sand/gravel sediments. The model uses the full size distribution of the bed surface, and based on a supposed nonlinear effect of sand content on gravel transport rate not included in previous models. This transport formula was implemented in a hydrodynamic model, which solves the three-dimensional Reynolds averaged Navier-Stokes (RANS) equations with the k-epsilon turbulence closure. Two types of test channels were defined to assess the suitability of the transport formula. The testing was carried out to focus on the capabilities of the sediment transport model for the modeling of the selective erosion included the bed armoring. The other reason of the testing was to investigate the sudden reaction of the river bed to a flood event. The results of the tests suggest that the numerical model is capable to reproduce the bed armoring process. Furthermore, the application of this model can be an appropriate way to investigate the changes in the bed level and in the surface size distribution as well.