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On equivalent roughness of mobile bed at high shear stress
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SYSNO ASEP 0328720 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title On equivalent roughness of mobile bed at high shear stress Author(s) Matoušek, Václav (UH-J) ORCID, SAI, RID
Krupička, Jan (UH-J) SAI, RIDSource Title Journal of Hydrology and Hydromechanics. - : Ústav pro hydromechaniku AV ČR, v. v. i.. - : Ústav hydrológie SAV - ISSN 0042-790X
Roč. 57, č. 3 (2009), s. 191-199Number of pages 9 s. Publication form on-line - on-line Language eng - English Country SK - Slovakia Keywords bed shear ; experiment ; hydraulic transport ; sediment transport Subject RIV BK - Fluid Dynamics R&D Projects GA103/06/0428 GA ČR - Czech Science Foundation (CSF) CEZ AV0Z20600510 - UH-J (2005-2011) UT WOS 000268906900006 DOI 10.2478/v10098-009-0018-9 Annotation The friction conditions at the top of a mobile bed are discussed for flows in the upper-plane-bed regime, i.e. for the flows with values of the bed Shields parameter larger than approximately 0.6. A special attention is devoted to flows of the bed Shields parameter bigger than 2. Experimental data for flows at high bed shear are collected from literature and new data are added from own measurements of flows of a 1.36-mm sand slurry in the 100-mm pipe loop of the Institute of Hydrodynamics. The paper analyses the data in order to evaluate a relationship among the equivalent roughness of the top of the bed and other relevant parameters. A semi-empirical formula is proposed that relates the equivalent roughness to the bed Shields parameter, the ratio of flow velocity and particle settling velocity, and the ratio of flow hydraulic radius and particle diameter. The formula is applicable primarily to flows of combined load (contact- and suspended loads together). Workplace Institute of Hydrodynamics Contact Soňa Hnilicová, hnilicova@ih.cas.cz, Tel.: 233 109 003 Year of Publishing 2010
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