A Two-Phase/Two-Layer Model for Fast and Heavily Loaded Transient Flows

Meurice, Robin [UCL] Soares Frazao, Sandra [UCL]

A 2D finite volume model aimed at simulating heavily loaded transient flows such as dam-flushes was presented. The shallow water equations are extended to a two-phase and two-layer model with variable solid concentrations in each layer. In contrast, the concentration of the mobile bed is considered to be constant. Following this approach, the inertia of the water and sediment mixture is better grasped by the model than by a simple bedload model solving the shallow water and the Exner equation. Nevertheless, spatio-temporal analyses made for different test cases pointed out the fact that the model may only be relevant when the transport in the lower layer is important to the whole flow. When the concentration in that layer is low or when the depth of that layer with respect to the whole water column is rather reduced, a bedload model may better behave. The model's scope hence looks to be coherent with the reason behind its development.