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Effect of roughness on the average and pulsating velocity characteristics
Conclusions 1. For all types of roughness the vertical distribution of the average velocities obeys the logarithmic law. 2. The dynamic roughness increases with increase in the geometric roughness. 3. With an increase of relative roughness of the bottom y0/H within limits from 0.5·10−3 to 6.4·10−3 the von Karman constant increases from 0.37 to 0.55 and then it decreases to 0.18. 4. The intensity of turbulence depends linearly on the relative roughness of the bottom. 5. The height of the near-bottom layer, determined from the position of the maximum value of the standard deviation of the longitudinal velocity component, increases with increase in the relative roughness of the bottom. 6. The intensity of the velocity fluctuations increases with increase in the diameter of the roughness projections. Inhomogeneity of the size of the roughness projections promotes an increase in the intensity of pulsations. In the case of a separated arrangement of the roughness projections the pulsation intensity also increases. 7. Channel flow has a layerwise eddy structure. We can assume that the axis of rotation of the eddies occurring near the bottom changes during their penetration into the mass of the flow.
Effect of roughness on the average and pulsating velocity characteristics
Conclusions 1. For all types of roughness the vertical distribution of the average velocities obeys the logarithmic law. 2. The dynamic roughness increases with increase in the geometric roughness. 3. With an increase of relative roughness of the bottom y0/H within limits from 0.5·10−3 to 6.4·10−3 the von Karman constant increases from 0.37 to 0.55 and then it decreases to 0.18. 4. The intensity of turbulence depends linearly on the relative roughness of the bottom. 5. The height of the near-bottom layer, determined from the position of the maximum value of the standard deviation of the longitudinal velocity component, increases with increase in the relative roughness of the bottom. 6. The intensity of the velocity fluctuations increases with increase in the diameter of the roughness projections. Inhomogeneity of the size of the roughness projections promotes an increase in the intensity of pulsations. In the case of a separated arrangement of the roughness projections the pulsation intensity also increases. 7. Channel flow has a layerwise eddy structure. We can assume that the axis of rotation of the eddies occurring near the bottom changes during their penetration into the mass of the flow.
Effect of roughness on the average and pulsating velocity characteristics
Melekhova, N. A. (Autor:in) / Mikhailova, N. A. (Autor:in) / Petrov, V. P. (Autor:in)
Hydrotechnical Construction ; 10 ; 595-601
01.06.1976
7 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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