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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Coupled modelling of shallow water flows over erodible bed
Coupled modelling of shallow water flows over erodible bed
For relatively slow shallow water flows with slow bed-load sediment transport, the bed-level is solved by conventionally
decoupling the hydrodynamic and morphodynamic systems, which usually yield relatively accurate results for very slow
bed-erosion processes. However, for those morphological evolution processes under intense water flow, in which the bed
deformation rate is comparable to hydraulic evolution and strongly coupled multiple physical processes exist, the
conventional decoupled numerical method for updating the bed level can not predict stable and accurate morphology due
to the instability and inaccuracy of the numerical scheme. This requires a more stable and accurate numerical method to
approximate the bed-load sediment fluxes terms under a rapidly morphological evolution. In order to avoid the instability
and inaccuracy of the conventional method for calculating fast bed level change under a rapidly varying flow, a strategy of
coupling the Exner-based equation in the hyperbolic system and approximating the bed-load fluxes using a Godunov-type
solver has attracted more attention from researchers. However, in most reported studies, the same local wave speeds for
both water flow and bed evolution systems are used in the flux solvers.
In the current study, a coupled model simulating water flows and bed-load transport with a novel local-wave estimator is
proposed. The eigenvalues of the 5กม5 Jacobian matrix are given using a general format including the bed-load coefficient
A􀭥 . The central-upwind method is adopted to approximate the numerical fluxes across the cell interfaces. Linear
reconstruction of variables with multi-dimensional slope limiter and the second-order TVD Runge-Kutta scheme are
employed to achieve higher accuracy in space and time, respectively
File Size : 337,424 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 18/08/2015
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