Rivers : Mathematical description of water movement over dune- covered river beds : Report on theoretical investigation

The development of a numerically fast flow model to predict the shear stresses and pressures on alluvial dunes is presented. As a first step a model based on a mixing layer approach to describe the separated flow and on a boundary layer method to describe the reattaching flow is treated. This model showed encouraging results of the boundary layer method. These results and discontinuity effects on the transition point of the relatively complicated mixing layer approach to the boundary layer method led to the appliance of boundary layer theory throughout the whole flow region above an alluvial dune. Additional assumptions based on dune-flow measurements and a flexible mathematical description of the velocity profile inside the boundary layer resulted model (WABED), which shows reasonable results of local bottom shear and local bottom pressures.