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Open AccessArticle

Influence of Gravel-Bed Porosity and Grain Orientation on Bulk Flow Resistance

Department of Civil and Environmental Engineering, Norwegian University of Science and Technology (NTNU), S.P.Andersens veg 5, 7491 Trondheim, Norway
Leichtweiß-Institut für Wasserbau, Technische Universität Braunschweig, 38106 Braunschweig, Germany
College of Harbour, Coastal and Offshore Engineering, Hohai University, Xikang road #1, Nanjing 210098, China
Author to whom correspondence should be addressed.
Water 2018, 10(5), 561;
Received: 19 March 2018 / Revised: 12 April 2018 / Accepted: 20 April 2018 / Published: 26 April 2018
(This article belongs to the Special Issue Turbulence in River and Maritime Hydraulics)
This paper presents results from experiments that were carried out to study the effect of porosity and grain orientation on flow resistance. Experiments were performed over three rough surfaces; a water-worked gravel-bed, its non-porous facsimile (cast-bed) and the rotated cast-bed (cast tiles rotated through 180°). The first two beds were used to isolate the influence of gravel-bed porosity on the bulk flow resistance and the rotated cast was used to study effect of the grain orientation on the flow resistance. The results showed that the rotated cast-bed exerted the highest flow resistance whereas the porous water-worked gravel-bed was, for comparable hydraulic boundary conditions, characterized by slightly higher flow resistance than its non-porous counterpart. The results from the bulk flow analysis were substantiated by a preliminary analysis of flow velocity data. View Full-Text
Keywords: flow resistance; roughness; gravel-bed rivers; casting technique flow resistance; roughness; gravel-bed rivers; casting technique
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MDPI and ACS Style

Navaratnam, C.U.; Aberle, J.; Qin, J.; Henry, P.-Y. Influence of Gravel-Bed Porosity and Grain Orientation on Bulk Flow Resistance. Water 2018, 10, 561.

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