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Aerodynamic roughness length of sandy beds and gravel beds
Environmental Earth Sciences, 2012A physical model was developed for the aerodynamic roughness length of gravel beds and sandy beds under different atmospheric stability conditions based on Monin–Obukhov similarity theory and dimensional analysis. The relationship between the roughness length, the properties of the roughness elements, the characteristics of the airflow, and an ...
Ping Lv, Zhibao Dong
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Effective Thermal Conductivity of Rough Spheres Packed Bed
Heat Transfer: Volume 1, 2003The effective thermal conductivity, ke, rigorously defined on the basis of the local volume averaging method, is an important parameter in porous media. The experimental and numerical results available in literature demonstrate that the kevalue is influenced by several parameters such as thermal and mechanical properties of the multiphase porous medium,
VANOLI L. +3 more
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Velocity Distribution in the Roughness Layer of Rough-Bed Flows
Journal of Hydraulic Engineering, 2004Several 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 ...
Vladimir Nikora +4 more
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Bed roughness produced by saltating sediment
Journal of Geophysical Research: Oceans, 1989Several expressions for characterizing bed roughness produced by a layer of saltating sediment have previously been proposed, and another is presented herein. These expressions relate the magnitude of the bottom roughness to the thickness of the near‐bed layer of saltating particles.
Patricia L. Wiberg, David M. Rubin
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Modelling Dynamic Bed Roughness Associated with Bed Form Development
2009In this study bed form development was quantified and used to calculate a dynamic bed roughness parameter. An algorithm that can be readily implemented into numerical models was developed and evaluated for two scenarios, with distinct flow conditions and sediment carrying capacities.
W B Rauen, B Lin, R A Falconer
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Surface roughness: capturing rough-bed river diversity
Channel geometry and bed surface roughness modulate the flow resistance of river channels, which is fundamental to the conveyance of water and sediment. In rough-bed rivers, where the flow is shallow relative to roughness height, there is notable uncertainty in flow resistance calculations based on sediment percentiles (D50 or D84) or the standard ...Robert Houseago +9 more
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Equivalent Roughness of Alluvial Bed
Journal of the Hydraulics Division, 1982The eguivalent roughness of a movable bed is considered. Relationships are given which can be used to determine the equivalent bed roughness from the bed material size and the bed-form dimensions. In the case of a plane bed the equivalent roughness is related to the D 9 0 of the bed material.
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Movable Bed Roughness in Alluvial Rivers
Journal of Hydraulic Engineering, 1999A method for the prediction of a movable bed roughness coefficient is proposed by relating the roughness parameter \iA to the nondimensional shear stress τ\u′\i\db/τ\i\dc\d5\d0 and the Froude number of flow. This relationship is tested with a large number of flume and field data from different sources, and also compared with other prediction methods ...
Weiming Wu, Sam S. Y. Wang
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Density Currents Dynamics over Rough Beds
Applied Mechanics and Materials, 2015Density currents are flows driven by density differences caused by suspended fine solid material, dissolved contents, temperature gradient or a combination of them. Reservoir sedimentation is often related to sediment transport by density currents. This sedimentation can block bottom outlets, reduce the capacity of reservoir and harms the dam power ...
Reza Nasrollahpour +4 more
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Influence of bed surface roughness on flow in rough-bed rivers
Riverbed surface roughness (or topography) modulates channel hydrodynamics, including the velocity and turbulence distributions, which underpin flood risk and sediment transport. Our recent research has presented the diversity of bed surface roughness found in bedrock and boulder-bed channels, prompting an investigation into the subsequent ...Robert Houseago +10 more
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