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Spatially-averaged turbulent flow over cubical roughness in wave-current co-existing environment
Abstract The paper describes an experimental study carried out in a laboratory flume to investigate the interaction of surface-wave with unidirectional current over cube mounted rough-bed (3D flow). The cubes were made of wood and were positioned at the channel-bed with different spacing. The spacing was chosen to represent different roughness types under different spacing conditions as: isolated roughness flow, wake interference flow and skimming flow. The three-dimensional velocity field was measured by an acoustic Doppler velocimetre (ADV). The study particularly focused on the changes induced in the spatially-averaged velocity profiles, turbulence intensities and Reynolds shear stress due to the superposition of waves of different frequencies on current-induced flow. Spatially-averaged velocity profiles show two distinct distributions: linear or exponential distribution below the roughness crest and logarithmic distribution above the roughness crest. It is found that the shift of the velocity profile depends strongly on the spacing of roughness elements. The profile of stream-wise turbulence intensity changes significantly below the roughness crest due to presence of surface wave, whereas bottom-normal spatially-averaged turbulence intensity does not change much with increase in wave frequency. Within the roughness crest near the bottom, the form-induced shear stress changes significantly from negative to positive value with change in roughness spacing, but is not affected much due to the presence of surface-wave.
Highlights Spatially-averaged flow is investigated Wave-current interaction in rough-bottom is studied Spatially-averaged turbulence intensity and turbulence stresses are evaluated
Spatially-averaged turbulent flow over cubical roughness in wave-current co-existing environment
Abstract The paper describes an experimental study carried out in a laboratory flume to investigate the interaction of surface-wave with unidirectional current over cube mounted rough-bed (3D flow). The cubes were made of wood and were positioned at the channel-bed with different spacing. The spacing was chosen to represent different roughness types under different spacing conditions as: isolated roughness flow, wake interference flow and skimming flow. The three-dimensional velocity field was measured by an acoustic Doppler velocimetre (ADV). The study particularly focused on the changes induced in the spatially-averaged velocity profiles, turbulence intensities and Reynolds shear stress due to the superposition of waves of different frequencies on current-induced flow. Spatially-averaged velocity profiles show two distinct distributions: linear or exponential distribution below the roughness crest and logarithmic distribution above the roughness crest. It is found that the shift of the velocity profile depends strongly on the spacing of roughness elements. The profile of stream-wise turbulence intensity changes significantly below the roughness crest due to presence of surface wave, whereas bottom-normal spatially-averaged turbulence intensity does not change much with increase in wave frequency. Within the roughness crest near the bottom, the form-induced shear stress changes significantly from negative to positive value with change in roughness spacing, but is not affected much due to the presence of surface-wave.
Highlights Spatially-averaged flow is investigated Wave-current interaction in rough-bottom is studied Spatially-averaged turbulence intensity and turbulence stresses are evaluated
Spatially-averaged turbulent flow over cubical roughness in wave-current co-existing environment
Singh, Santosh Kumar (author) / Debnath, Koustuv (author) / Mazumder, Bijoy S. (author)
Coastal Engineering ; 114 ; 77-85
2016-04-11
9 pages
Article (Journal)
Electronic Resource
English
Spatially-averaged turbulent flow over cubical roughness in wave-current co-existing environment
| British Library Online Contents | 2016
Spatially-averaged turbulent flow over cubical roughness in wave-current co-existing environment
| Online Contents | 2016
Spatially-averaged turbulent flow over cubical roughness in wave-current co-existing environment
| British Library Online Contents | 2016
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