Comparison of Coupled and Semicoupled Numerical Models for Alluvial Channels
Publication: Journal of Hydraulic Engineering
Volume 124, Issue 8
Abstract
Contrary to general statements in the literature, the investigations reported 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 variations in alluvial channels. Vertically averaged Navier-Stokes equations 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 implicit scheme. Both models are applied to predict bed-level changes due to sediment overloading and sediment shut-off. The computed results compare satisfactorily with the experimental results obtained in a laboratory flume. The results obtained by the semicoupled model are relatively close to that of the fully coupled model. Because the former algorithm 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.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Abbott, M. B. (1979). Computational hydraulics: elements of the theory of free surface flow. Pitman Publishing Limited, London, U.K.
2.
Bhallamudi, S. M., and Chaudhry, M. H.(1991). “Numerical modeling of aggradation and degradation in alluvial channels.” J. Hydr. Engrg., ASCE, 117(9), 1145–1164.
3.
Chapman, R. S., and Kuo, C. Y.(1985). “Application of the two-equation turbulence to a two-dimensional, steady, free surface flow problem with separation.”Int. J. Numer. Methods in Fluids, 5, 257–268.
4.
Chaudhry, M. H. (1993). Open-channel flow. Prentice Hall, Englewood Cliffs, N.J.
5.
Correia, R. P., Krishnappan, B. G., and Graf, W. H.(1992). “Fully coupled unsteady mobile boundary flow model.”J. Hydr. Engrg., ASCE, 118(3), 476–494.
6.
Cunge, J. A., Holly, F. M., and Verwey, A. (1980). Practical aspects of computational river hydraulics, Pitman Advanced Publishing Program, London, U.K.
7.
Hoffmann, K. A. (1989). Computational fluid dynamics for engineers. Education Engineering System, Austin, Tex.
8.
Holly, F. M., and Rahuel, J. L.(1990). “New numerical physical framework for mobil bed modeling, part 1.”J. Hydr. Res., Delft, The Netherlands, 28(4), 401–416.
9.
Holly, F. M., Yang, J. C., Schwarz, J., Schaefer, J., Hsu, S. H., and Einhellig, R. (1990). “CHARIMA: numerical simulation on unsteady water and sediment movement in multiply connected networks of movable-bed channels.”IIHR Rep. No. 343, Iowa Institute of Hydraulic Research, University of Iowa, Iowa City, Iowa.
10.
Kuipers, J., and Vreugdenhil, C. B. (1973). “Calculations of two-dimensional horizontal flow.”Delft Hydr. Lab. Rep. S 163 Part 1, Delft Hydraulics Laboratory, Delft, The Netherlands.
11.
Lu, J.-Y., and Shen, H. W.(1986). “Analysis and comparisons of degradation models.”J. Hydr. Engrg., ASCE, 112(4), 281–299.
12.
Lyn, D. A.(1987). “Unsteady sediment transport modeling.”J. Hydr. Engrg., ASCE, 113(1), 1–15.
13.
Molls, T., and Chaudhry, M. H.(1995). “Depth-averaged open-channel flow model.”J. Hydr. Engrg., ASCE, 121(6), 453–465.
14.
Shimizu, Y., and Itakura, T.(1989). “Calculation of bed variation in alluvial channels.”J. Hydr. Div., ASCE, 115(3), 367–384.
15.
Soni, J. P., Garde, R. J., and Ranga Raju, K. G.(1980). “Aggradation in streams due to overloading.”J. Hydr. Engrg., ASCE, 106(1), 117–132.
16.
Spasojevic, M., and Holly, F. M.(1990). “2-D bed evolution in natural water courses: new simulation approach.”J. Wtrwy., Port, Coast., and Oc. Engrg., ASCE, 116(4), 425–443.
17.
Struiksma, N., Olsen, K. W., Flokstra, C., and De Vriend, H. J.(1985). “Bed deformation in curved alluvial channels.”J. Hydr. Res., Delft, The Netherlands, 23(11), 57–79.
18.
Suryanarayana, B. (1969). “Mechanics of degradation and aggradation in a laboratory flume,” PhD thesis, Colorado State University, Fort Collins, Colo.
19.
Towne, C. E., Schwab, J. R., and Bui, T. T. (1992). “PROTEUS two-dimensional Navier Stokes computer code—version 2.0.”NASA Tech. Memo. 102551, NASA Lewis Research Center, Cleveland, Ohio.
20.
Younus, M., and Chaudhry, M. H.(1994). “A depth-averaged K-ε model for the computation of free-surface flow.”J. Hydr. Res., Delft, The Netherlands, 32(3), 415–443.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 124 • Issue 8 • August 1998
Pages: 794 - 802
Copyright
Copyright © 1998 American Society of Civil Engineers.
History
Published online: Aug 1, 1998
Published in print: Aug 1998
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.