COMPARISON OF COUPLED AND SEMICOUPLED NUMERICAL-MODELS FOR ALLUVIAL CHANNELS

Citation
Aa. Kassem et Mh. Chaudhry, COMPARISON OF COUPLED AND SEMICOUPLED NUMERICAL-MODELS FOR ALLUVIAL CHANNELS, Journal of hydraulic engineering, 124(8), 1998, pp. 794-802
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Water Resources","Engineering, Civil","Engineering, Mechanical
ISSN journal
0733-9429
Volume
124
Issue
8
Year of publication
1998
Pages
794 - 802
Database
ISI
SICI code
0733-9429(1998)124:8<794:COCASN>2.0.ZU;2-4
Abstract
Contrary to general statements in the literature, the investigations r eported in this paper show that semicoupled models are not necessarily unstable and give results comparable to those of coupled models. For this purpose, a two-dimensional model is developed to calculate bed va riations in alluvial channels. Vertically averaged Navier-Stokes equat ions in transformed coordinates are numerically solved in conjunction with the sediment transport equation for the bed load. These equations are solved simultaneously in a fully coupled model and separately in a semicoupled model using the Beam and Warming alternating-direction i mplicit scheme. Both models are applied to predict bed-level changes d ue to sediment overloading and sediment shut-off. The computed results compare satisfactorily with the experimental results obtained in a la boratory flume. The results obtained by the semicoupled model are rela tively close to that of the fully coupled model. Because the former al gorithm permits any sediment formula and armoring effect to be easily incorporated, the semicoupled model appears to be more attractive for general applications to real-life systems than the coupled model.