American Society of Civil Engineers


Turbulence Statistics in an Open-Channel Flow over a Rough Bed


by Sandeep Bomminayuni, (School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332. E-mail: sandeepbommin@gmail.com) and Thorsten Stoesser, (corresponding author), M.ASCE, (School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332. E-mail: thorsten@ce.gatech.edu)

Journal of Hydraulic Engineering, Vol. 137, No. 11, November 2011, pp. 1347-1358, (doi:  http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0000454)

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Document type: Journal Paper
Abstract: This paper presents the results of a large-eddy simulation (LES) of turbulent flow over a channel bed artificially roughened by hemispheres. The Reynolds number of the flow based on the channel depth is 13,680 at a relatively low submergence of 3.42. First- and second-order statistics are compared with corresponding laboratory experiments to validate the LES. The effect of roughness heterogeneity on higher-order statistics is quantified and discussed. The contribution of the dominating turbulent events (i.e., sweeps, ejections) to the Reynolds stress and the anisotropy of turbulence are quantified. Visualizations of the complex three-dimensional turbulence structures reveal the occurrence of a number of different vortex types in the flow. The contribution of turbulence structures to the turbulent kinetic energy and their scaling is assessed through proper orthogonal decomposition.


ASCE Subject Headings:
Turbulence
Bed roughness
Anisotropy
Simulation
Decomposition
Statistics
Open channel flow

Author Keywords:
Turbulence
Roughness
Turbulence anisotropy
Large-eddy simulation
Coherent structures
Proper orthogonal decomposition