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An evaluation of bed shear stress under turbid flows

An evaluation of bed shear stress under turbid flows
An evaluation of bed shear stress under turbid flows
This paper investigates the effect of various turbidity levels on the drag coefficient and bed shear stress in decelerating flows over a smooth bed. Turbid flows were simulated in a laboratory annular flume (Lab Carousel) using clay suspensions of different known mass concentrations. Flow velocity measurements were taken in the turbulent boundary layer and the values of bed drag coefficient and shear stress were calculated using the method of flow deceleration. Results showed that the bed drag coefficient responds significantly to an increase in the suspended sediment concentration (up to 20 g\L) showing a decrease of up to 50% in drag due to turbulence suppression. However, subsequent increases in mass concentration resulted in an increase in the drag coefficient reaching the clear water value at approximately 200 g\L because of the influence of viscosity. Thus the application of the law of the wall in flows of high concentrations of suspended cohesive sediments up to 200 g\L results in overestimation of the bed shear stress.
drag coefficient, bed shear stress, clay suspensions
0148-0227
C04008-[8pp]
Thompson, C.E.L.
2a304aa6-761e-4d99-b227-cedb67129bfb
Amos, C.L.
d0a18a13-bccd-4fdc-8901-aea595d4ed5c
Angelaki, M.
8c66e5f3-9bf9-4e7b-bb85-695f22b6bb44
Jones, T.E.R.
accf7332-d728-493f-b684-b2fca3555378
Binks, C.E.
52ed9323-7ce0-4e5b-b5b1-7c3bffd90554
Thompson, C.E.L.
2a304aa6-761e-4d99-b227-cedb67129bfb
Amos, C.L.
d0a18a13-bccd-4fdc-8901-aea595d4ed5c
Angelaki, M.
8c66e5f3-9bf9-4e7b-bb85-695f22b6bb44
Jones, T.E.R.
accf7332-d728-493f-b684-b2fca3555378
Binks, C.E.
52ed9323-7ce0-4e5b-b5b1-7c3bffd90554

Thompson, C.E.L., Amos, C.L., Angelaki, M., Jones, T.E.R. and Binks, C.E. (2006) An evaluation of bed shear stress under turbid flows. Journal of Geophysical Research, 111 (C4), C04008-[8pp]. (doi:10.1029/2005JC003287).

Record type: Article

Abstract

This paper investigates the effect of various turbidity levels on the drag coefficient and bed shear stress in decelerating flows over a smooth bed. Turbid flows were simulated in a laboratory annular flume (Lab Carousel) using clay suspensions of different known mass concentrations. Flow velocity measurements were taken in the turbulent boundary layer and the values of bed drag coefficient and shear stress were calculated using the method of flow deceleration. Results showed that the bed drag coefficient responds significantly to an increase in the suspended sediment concentration (up to 20 g\L) showing a decrease of up to 50% in drag due to turbulence suppression. However, subsequent increases in mass concentration resulted in an increase in the drag coefficient reaching the clear water value at approximately 200 g\L because of the influence of viscosity. Thus the application of the law of the wall in flows of high concentrations of suspended cohesive sediments up to 200 g\L results in overestimation of the bed shear stress.

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More information

Published date: April 2006
Additional Information: Index Terms: 4558 Oceanography: Physical: Sediment transport (1862); 4217 Oceanography: General: Coastal processes; 4599 Oceanography: Physical: General or miscellaneous.
Keywords: drag coefficient, bed shear stress, clay suspensions

Identifiers

Local EPrints ID: 28707
URI: http://eprints.soton.ac.uk/id/eprint/28707
ISSN: 0148-0227
PURE UUID: 0324c865-5151-4dba-bdba-0abc33264856
ORCID for C.E.L. Thompson: ORCID iD orcid.org/0000-0003-1105-6838

Catalogue record

Date deposited: 04 May 2006
Last modified: 16 Mar 2024 03:14

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Contributors

Author: C.E.L. Thompson ORCID iD
Author: C.L. Amos
Author: M. Angelaki
Author: T.E.R. Jones
Author: C.E. Binks

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