Champ de vitesses et contraintes de cisaillement dans un collecteur d’assainissement

Abstract

The presence of sediment at the bottom of the collectors is of interest for hydraulic and environmental reasons. Design rules enable avoiding silting in a wide range of situation, but are not suited for accurately assessing risk for a particular facility. The stress at the bottom is a determining parameter for the processes of sedimentation and erosion and results from the velocity field in a cross section. This article presents an experimental and numerical approach of the space distribution of the velocities and shear stresses in a collector of sewers network. The results show that, for the narrow channels, it is necessary to take into account the three-dimensional character of the flow. Numerical modeling provides the lower cost for the results that is difficult to acquire in experiments. On the other hand a total evaluation of the average shear stress seems less adapted to describe the reality of shear stress in the section.