Velocity and Concentration Profiles in Sheet-Flow Layer of Movable Bed
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Abstract
Sheet-flow layer of movable bed in steady currents has been investigated experimentally, using four kinds of sediment. Velocity and concentration profiles as well as flow resistance were measured inside and outside the sheet-flow layer. The range of fall-velocity–to–friction-velocity ratio ( w /U f) achieved in the study is 0.2 <w/U f< 1.7, which covers both the suspension-mode sediment transport ( w /U f< 0.8–1), and the no-suspension-mode sediment transport ( w /U f> 0.8–1). In the suspension-mode sheet flow, the flow resistance is found to depend not only on the Shields parameter but also on a parameter involving w . Measured velocity profiles are found to follow the logarithmic law near the bed, outside the sheet-flow layer, whereas inside the sheet-flow layer, they satisfy a power law. Measured concentration profiles, on the other hand, indicate a linear variation with the distance from the bed inside the sheet flow-layer near the bed, whereas away from the bed, the familiar Rouse distribution is satisfied. Evidently, sediment transport in the sheet-flow layer is influenced by the turbulent bursting process.
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References
1.
Bagnold, R. A. (1966). “An approach to the sediment transport problem from general physics.”Profl. Paper No. 422-I, U.S. Geological Survey, U.S. Govt. Printing Ofc., Washington, D.C.
2.
Batchelor, G. K. (1965). “The motion of small particles in turbulent flow.”Proc., 2nd Australian Conf. on Hydr. and Fluid Mech., Univ. of Auckland, Auckland, Australia, 019–041.
3.
Cantwell, B. J.(1981). “Organized motion in turbulent flow.”Ann. Rev. Fluid Mech., 13, 457–515.
4.
Dyer, K. R., and Soulsby, R. L.(1988). “Sand transport on the continental shelf.”Ann. Rev. Fluid Mech., 20, 295–324.
5.
Engelund, F., and Fredsøe, J.(1976). “A sediment transport model for straight alluvial channels.”Nordic Hydro., 7, 293–306.
6.
Grass, A. J. (1983). “The influence of boundary layer turbulence on the mechanics of sediment transport.”Proc., Euromech 156/Mech. of Sediment Transport, A. A. Balkema, Rotterdam, The Netherlands, 3–17.
7.
Monin, A. S., and Yaglom, A. M. (1973). Statistical fluid mechanics: mechanics of turbulence . MIT Press, Cambridge, Mass.
8.
Nnadi, F. N., and Wilson, K. C.(1992). “Motion of contact-load particles at high shear stress.”J. Hydr. Engrg., ASCE, 118(12), 1670–1684.
9.
Nnadi, F. N., Shaw, J. K., and Wilson, K. C. (1993). “Sheet-flow transport by unidirectional motion and asymmetric waves.” Can. Coastal Engrg. Conf., Vancouver, Canada.
10.
Rotta, J. C. (1962). “Turbulent boundary layers in incompressible flow.”Progress in aeronautical sciences, A. Ferri, D. Küchemann, and L. H. G. Sterne, eds., The Macmillan Company, New York, N.Y., 5–212.
11.
Rouse, H.(1937). “Modern conceptions of the mechanics of fluid turbulence.”Trans., ASCE, New York, N.Y., 102, 463–543.
12.
Schlichting, H. (1979). Boundary-layer theory . McGraw-Hill Book Co., Inc., New York, N.Y.
13.
Sumer, B. M. (1986). “Recent developments on the mechanics of sediment suspension.”Transport of suspended solids in open channels, W. Bechteler, ed., A. A. Balkema, Rotterdam, The Netherlands, 3–22.
14.
Vanoni, V. A. (1975). Sedimentation engineering . ASCE Manuals and Rep. on Engrg. Pract., 54, ASCE, New York, N.Y.
15.
Vanoni, V. A., and Brooks, N. H. (1957). “Laboratory studies of the roughness and suspended load of alluvial streams.” Caltech Sedimentation Lab., Pasadena, Calif., M.R.D. Sediment Ser. No. 11.
16.
Wilson, K. C. (1965). “Derivation of regime equations from relationships for pressurized flow by use of the principle of minimum energy-degradation rate,” PhD thesis, Queen's Univ., Kinston, Ontario, Canada.
17.
Wilson, K. C.(1987). “Analyses of bed-load motion at high shear stress.”J. Hydr. Engrg., ASCE, 113(1), 97–103.
18.
Wilson, K. C. (1988). “Frictional behaviour of sheet flow.”Prog. Rep. No. 67, Inst. of hydrodyn. and Hydr. Engrg., Technical Univ. of Denmark, DK-2800 Lyngby, Denmark, 11–22.
19.
Wilson, K. C.(1989). “Mobile bed friction at high shear stress.”J. Hydr. Engrg., ASCE, 115(6), 825–830.
20.
Wilson, K. C., and Nnadi, F. N.(1990). “Behaviour of mobile beds at high shear stress.”Proc., 22nd Coastal Engrg. Conf., ASCE, New York, N.Y., 3, 2536–2541.
21.
Yalin, M. S. (1992). River Mechanics. Pergamon Press, Inc., Tarrytown, N.Y.
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Published In
Journal of Hydraulic Engineering
Volume 122 • Issue 10 • October 1996
Pages: 549 - 558
Copyright
Copyright © 1996 American Society of Civil Engineers.
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Published online: Oct 1, 1996
Published in print: Oct 1996
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