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Spatially-averaged turbulent flow characteristics over ribbed surface in presence of unidirectional wave over steady current
Highlights Turbulence characteristics using spatiotemporal averaging approach in pulsating flow environment Shannon entropy for describing the degree of disorderness under rib influence in wave environment Spatial momentum exchange, form induced shear stress for wave influenced spatio-temporal averaging Influence of roughness spacing and flow periodicity on wave induced turbulent flow
Abstract The paper presents an experimental study on the characterization of the effect of surface-wave of different frequencies on spatially-averaged turbulent statistics over a rough bed. The model roughness comprised of periodically positioned, transverse square ribs that extended across the whole width of the channel. The three-dimensional turbulent velocity fluctuations were mapped by an acoustic Doppler velocimeter (ADV) in the flow domain at high resolution. These data were analyzed to examine time-space averaged turbulence parameters of the double averaged Navier Stokes equations and momentum transfer under the influence of the rough boundary. Further, Shannon entropy at different vertical position were also evaluated to develop insight into the energy transfer mechanism. Results show a reduction in the apparent roughness height and an increase of the intensity of turbulence under surface wave influence. Furthermore, the superposition of waves led to the increase in turbulence production and showed maximum values at the roughness layer as compared to buffer layer in current-only flow over plane bed.
Spatially-averaged turbulent flow characteristics over ribbed surface in presence of unidirectional wave over steady current
Highlights Turbulence characteristics using spatiotemporal averaging approach in pulsating flow environment Shannon entropy for describing the degree of disorderness under rib influence in wave environment Spatial momentum exchange, form induced shear stress for wave influenced spatio-temporal averaging Influence of roughness spacing and flow periodicity on wave induced turbulent flow
Abstract The paper presents an experimental study on the characterization of the effect of surface-wave of different frequencies on spatially-averaged turbulent statistics over a rough bed. The model roughness comprised of periodically positioned, transverse square ribs that extended across the whole width of the channel. The three-dimensional turbulent velocity fluctuations were mapped by an acoustic Doppler velocimeter (ADV) in the flow domain at high resolution. These data were analyzed to examine time-space averaged turbulence parameters of the double averaged Navier Stokes equations and momentum transfer under the influence of the rough boundary. Further, Shannon entropy at different vertical position were also evaluated to develop insight into the energy transfer mechanism. Results show a reduction in the apparent roughness height and an increase of the intensity of turbulence under surface wave influence. Furthermore, the superposition of waves led to the increase in turbulence production and showed maximum values at the roughness layer as compared to buffer layer in current-only flow over plane bed.
Spatially-averaged turbulent flow characteristics over ribbed surface in presence of unidirectional wave over steady current
Raushan, Pankaj Kumar (author) / Paul, Arnov (author) / Singh, Santosh Kumar (author) / Debnath, Koustuv (author)
Applied Ocean Research ; 100
2020-03-30
Article (Journal)
Electronic Resource
English
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