Author(s): Hans Bihs; Nils Reidar B. Olsen
Keywords: No Keywords
Abstract: In the present paper a three-dimensional numerical model is used to model the local scour development around a trapezoidal abutment in a rectangular laboratory flume. The numerical results are compared with measurements from experiments and agree reasonable well. The numerical model solves the unsteady Reynolds-averaged-Navier-Stokes equations in all three dimensions to compute the water flow. The SIMPLE method is used to find the non-hydrostatic pressure. Turbulence is computed with the k-model. A convection-diffusion equation is solved to calculate the suspended sediment concentration. Sediment continuity in combination with an empirical formula is used to capture the bed load transport and the resulting bed changes. The present study focuses on the threshold of non-cohesive sediment motion on sloping beds and several formulas are tested. When the sloping bed exceeds the angle of repose, the bed slope is corrected with a sand slide algorithm.