Coupled numerical modelling of bed-erosion under rapid shallow water flows.

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Abdolmajid Mohammadian, Xin Liu

Tuesday 30 june 2015

16:00 - 16:15h at Oceania (level 0)

Themes: (T) Sediment management and morphodynamics, (ST) River morphodynamics

Parallel session: 7B. Sediment - River

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This paper presents a coupled model with novel wave speeds estimators which can reduce the excessive numerical diffusion comparing with other reported coupled model. To solve the hyperbolic governing bed-load sediment transport equation using a Godunov type Central-upwind scheme, a novel scheme estimating the numerical fluxes of bed-load terms is proposed using a different pair of bonding waves. The two-dimensional (2-D) shallow water equations (SWEs) are adopted to solve the hydrodynamic component. The bed-level is updated by an Exner equation containing bed-load sediment transport as numerical flux terms. A general form of a bed-load transport formula with a complex definition of the bed-load coefficient is applied to calculate a universal solution of the eigenvalues of the Jacobian Matrix. The linear reconstruction of variables with a minmod limiter and the third-order Runge-Kutta scheme are employed to achieve higher accuracy in space and time. The proposed coupled model with novel wave estimators shows better accuracy than other reported coupled models, which are verified by several numerical tests.