The role of a movable sandy-bed in modelling open-channel flow

Abstract

Sediment transport in rivers is important regarding to environmental and hydro-engineering issues. The complexity of this phenomenon derives on several assumptions for its theoretical analysis. One of these assumptions is to consider the water density and viscosity as constants; another is to neglect the influence of the flow through the porous medium on the water velocity profile. The presence of a movable sandybed is determinant for the variation of the fluid’s density and viscosity because of the processes that take place on the boundary between the porous medium and the fluid in motion. This paper describes at a glance some experimental investigations on how the water density varies as a function of the depth, velocity and channel roughness. In addition, the flow through the sandy layer is not neglected because a numerical model is developed to find the velocity field on the boundary between the bed and the water.