Dam-break flow in a channel with a sudden enlargement

Dam-break flows are usually simulated by solving the shallow-water equations, neglecting the turbulent stresses. However, in some situations like a flow in a channel with a sudden enlargement, features such as re-circulating flows may appear, that are generally not accurately modelled. The aim of the work presented in this paper is to try to answer the question whether turbulent stresses should be included in the shallow-water equations to improve the numerical results in such situations. Based on the CADAM experience, new laboratory experiments on both steady and dam-break flow in a channel with a sudden enlargement were performed and carefully observed by means of several measurement devices. Then, a Roe-type finite-volume scheme is developed to solve the adapted shallow-water equations including the turbulent stresses. Both firstand second-order spatial accuracy are considered. Finally, the numerical simulations are compared to the measurements in both the steady flow situation and in the dam-break flow. Interesting results are obtained, but at this stage no clear answer can be given to the question whether turbulent stresses are needed to accurately model dam-break flows.