Author(s): Giorgio Rosatti; Luigi Fraccarollo
Linked Author(s): Giorgio Rosatti
Keywords: Well-balanced scheme; Riemann solvers; Non-conservative term; Mobile-bed models; Sediment transport
Abstract: In this paper we deal with the numerical computation of one-dimensional, unsteady, freesurface flows over mobile-bed. We focus on flows characterized by high concentration of sediments and strong interaction between flow and bottom dynamics, as in hyperconcentrated- and debris-flows. These features are fully considered in the adopted system of equations. Challenging in its numerical approximation is the preservation of the coupling and the treatment of a non-conservative flux in the momentum equation. In order to devise a new Godunov-type approach, we used the peculiar features of the Riemann problem associated with the mobile-bed phenomena. The scheme we developed is based on two supports: wellbalanced treatment of the variable updating at the new time-level and flux evaluation by specific approximated solvers of the intercell Riemann problem. The properties of the new numerical strategy (named AWB) are exploited in cases of practical interest, where wave interaction and friction effects makes the flow rather complex. The obtained results point out that the new method is able to predict faithfully the overall behaviour of the solution and of any type of waves. The use of AWB, in this one-dimensional frame, is therefore fostered in representing rapid transients in river/torrent flows with movable bed.
Year: 2007