In: Journal of Hydrology and Hydromechanics, vol. 65, no. 1
Prashanth Hanmaiahgari - Vesselina Roussinova - Ram Balachandar
Detaily:
Rok, strany: 2017, 35 - 48
Kľúčové slová:
Turbulence; Open channel; Bedforms; Higher-order moments; PIV; Quadrant analysis.
URL originálneho zdroja: http://www.ih.sav.sk/jhh
O článku:
Turbulence of flow over mobile bedforms in natural open channels is not yet clearly understood. An attempt is made in this paper to determine the effect of naturally formed mobile bedforms on velocities, turbulent intensities and turbulent stresses. Instantaneous velocities are measured using a two-dimensional particle image velocimetry (PIV) to evaluate the turbulence structure of free surface flow over a fixed (immobile) bed, a weakly mobile bed and a temporally varying mobile bed with different stages of bedform development. This paper documents the vertical distribution of ve-locity, turbulence intensities, Reynolds shear stress and higher-order moments including skewness and turbulent diffu-sion factors. Analysis of the velocity distributions shows a substantial decrease of velocity near the bed with increasing bedform mobility due to increased friction. A modified logarithmic law with a reduced von Kármán constant and in-creased velocity shift is proposed for the case of the mobile bedforms. A significant increase in the Reynolds shear stress is observed in the mobile bedforms experiments accompanied by changes over the entire flow depth compared to an im-mobile bed. The skewness factor distribution was found to be different in the case of the flow over the mobile bedforms. All higher-order turbulence descriptors are found to be significantly affected by the formation of temporally varying and non-equilibrium mobile bedforms. Quadrant analysis indicates that sweep and outward events are found to be dominant in strongly mobile bedforms and govern the bedform mobility.
Ako citovať:
ISO 690:
Hanmaiahgari, P., Roussinova, V., Balachandar, R. 2017. Turbulence characteristics of flow in an open channel with temporally varying mobile bedforms. In Journal of Hydrology and Hydromechanics, vol. 65, no.1, pp. 35-48. 0042-790X (until 2019) .
APA:
Hanmaiahgari, P., Roussinova, V., Balachandar, R. (2017). Turbulence characteristics of flow in an open channel with temporally varying mobile bedforms. Journal of Hydrology and Hydromechanics, 65(1), 35-48. 0042-790X (until 2019) .