Physical and numerical modeling of overbank flow with a groyne on the floodplain
A. Bourdat, N. Rivière, Y. Peltier, S. Proust, F. Thollet, A. Paquier (2008)



This paper focuses on both physical and numerical modeling of flow in the vicinity of a groyne, blocking off the floodplain of an asymmetric compound channel, and perpendicular to the main flow direction. Experiments were conducted in a laboratory flume and in a small-scale model. Various lengths of groyne d were used in both the laboratory flume and the small-scale model. Water levels, ve-locity field and spreading of the recirculation zone behind the obstacle were measured for five flow configurations. The influence on the flow parameters of aspect ratio d/B (where B is the total width of the channel), of total discharge Q and of relative depth ratio hr were examined. Particularly, a hydraulic disjunction may occur between the subcritical flow and the supercritical flow respectively located up-stream and immediately downstream the obstacle, depending on the values of discharge Q and aspect ratio d/B. Flows were simulated with the 2D-H program RUBAR 20 (Cemagref). Two simple turbu-lence closures that are often used by engineers were tested: a constant eddy viscosity and the Elder's model u*, h. Simulations are compared to experimental measurements, focusing on the streamwise profiles of water level and discharge distribution across the channel, and on the spreading of the recir-culation zone. The influence of the turbulence model on flow parameters is then investigated.

Mots clés : chenal, main, modèle réduit, eau, acculturation, remblai, simulation, influence, aspect, lit majeur, modele numerique, ecoulement, canal experimental, simulation numérique, modele bidimensionnel, compound channel, groyne, recirculation zone, physical modeling, 2d-h modeling