High Resolution Reconstruction techniques for sediment transport in shallow water flows

Khawar Rehman, Yong-Sik Cho

Tuesday 30 june 2015

13:00 - 13:03h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling, Poster pitches

Parallel session: Poster pitches: 5A. Sediment - Erosion

In this study, a numerical approximation is proposed for bed load sediment transport for rapidly varying flows. Hydrodynamics and morphodynamics of the flow are modeled by two-dimensional Saint Venant and sediment continuity equations, respectively. The equations are coupled and the solution is evolved in one time step by the Godunov type finite volume method. For temporal discretization a third-order TVD Runge-Kutta method is used. For spatial accuracy, gradient reconstruction is performed by two high resolution methods; A third order Weighted Essentially Non oscillatory (WENO) scheme, and another gradient reconstruction together with a limiting technique. Both techniques are employed on unstructured triangular meshes, which are advantageous over structured meshes in case local grid refinement is desired in vicinity of abrupt geometry modulations. These methods reconstruct cell centered variables at interface of control volume for accurate approximation of flow information. The effects of both the reconstruction methods on the convergence speed of the coupled system of equations are investigated in detail. Fluxes at the interfaces are computed by approximate Riemann solvers. The applicability of the proposed model for a hyperbolic system is studied by simulating several test cases. Keywords: WENO scheme, Sediment-transport, upwind finite volume method, Shallow water equations, Exner equation, Approximate Riemann Solvers