Non-uniformity and layering in sediment transport modelling 1: flume simulations

Abstract

The development and validation of an integrated numerical sediment transport model capable of solving both uniform and non-uniform transport equations while calculating grain size distributions is presented. The model is coupled with external hydrodynamic codes which provide flow field and bed shear stress patterns. Transport equations are solved for an unlimited number of sediment size fractions. Two validation experiments involving unsteady flow in a channel bend and steady flow in a flume with lateral contraction were considered. Good agreement with measured bed deformations was found for non-uniform calculations with an exchange layer, whereas both uniform and non-uniform computations without the exchange layer resulted in comparably larger differences. In the channel bend experiment, the presence of an exchange layer was essential for achieving accurate modelling results, while its role was less pronounced in the lateral contraction experiment. Moreover, the sorting coefficient of the bed material was found to be a suitable indicator for estimating the applicability of uniform transport equations.