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Velocity Distribution in the Roughness Layer of Rough-Bed Flows |
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| Authors: | Vladimir Nikora Katinka Koll Ian McEwan Stephen McLean Andreas Dittrich |
| Affiliation: | 1Principal Scientist, Freshwater Hydrodynamics, National Institute of Water and Atmospheric Research, P.O. Box 8602, Christchurch, New Zealand. 2Research Associate, Institute of Hydraulics, Univ. of Braunschweig, Braunschweig, Germany. 3Reader, Dept. of Engineering, Univ. of Aberdeen, Aberdeen, AB24 3UE, UK. 4Professor, Dept. of Mechanical and Environmental Engineering, Univ. of California at Santa Barbara, Santa Barbara, CA. 5Professor, Institute of Hydraulics, Univ. of Braunschweig, Braunschweig, Germany. |
| Abstract: | Several models for the vertical distribution of the double-averaged (in time and in the plane parallel to the mean bed) longitudinal velocity in the flow region between roughness troughs and roughness tops are suggested. We found that the same model for velocity distribution may be applicable to a range of flow conditions and roughness types, which share some common features. The suggested models for velocity distribution in the near-bed region are: (1) Constant velocity; (2) exponential velocity distribution; and (3) linear velocity distribution. The measured velocity distributions may be approximated by a single model or by a combination of models depending on roughness geometry and flow conditions. The validity of these models for velocity distribution is supported by laboratory data. |
| Keywords: | Open channel flow Turbulent flow Velocity distribution Roughness Channel beds |