Bed-Load Sediment Transport on Large Slopes: Model Formulation and Implementation within a RANS Solver
Publication: Journal of Hydraulic Engineering
Volume 134, Issue 10
Abstract
Standard bed-load sediment-transport formulas are extended using basic mechanical principles to include gravitational influence on large slopes of arbitrary orientation. The resulting sediment fluxes are then incorporated into a morphodynamics model in a general-purpose, three-dimensional, finite-volume, Reynolds-averaged Navier–Stokes (RANS) code. Major features are: (1) the downslope component of weight is combined with the fluid stress to form an effective bed stress (similar to the work of Wu in 2004); (2) the critical effective stress is reduced in proportion to the component of gravity normal to the slope; (3) a simple flux-based model for avalanching is implemented as a numerical means of preventing the local slope from exceeding the angle of repose; (4) an entirely vectorial formulation of bed-load transport is developed to account for arbitrary surface orientation; and (5) methods for reducing numerical instability in the morphodynamics equation are described. Sample computations are shown for scour and accretion in a channel bend and for the movement of sand mounds on erodible and nonerodible bases.
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Acknowledgments
This paper forms part of a joint program of work between the Universities of Manchester and Oxford to develop an understanding (through laboratory and theoretical studies) of the evolution of sandbanks. The work is funded by the Engineering and Physical Research Council (Grant Nos. GR/S73396 and GR/S73042). The writers express their thanks for the provision of experimental data to Professor S. Kawai (channel bend) and Dr. J. Huang and Ms. I. Garcia-Hermosa (moving sand mounds).
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Information
Published In
Journal of Hydraulic Engineering
Volume 134 • Issue 10 • October 2008
Pages: 1440 - 1451
Copyright
© 2008 ASCE.
History
Received: Jan 19, 2007
Accepted: Jan 30, 2008
Published online: Oct 1, 2008
Published in print: Oct 2008
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