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Large-Eddy Simulation of Turbulent Flow over a Fixed Two-Dimensional Dune |
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| Authors: | Wusi Yue Ching-Long Lin Virendra C Patel |
| Affiliation: | 1Postdoctoral Fellow, Dept. of Geography and Environmental Engineering, The Johns Hopkins Univ., 3400 N. Charles St., Baltimore, MD 21218. E-mail: yue@jhu.edu 2Associate Professor, Dept. of Mechanical and Industrial Engineering, and IIHR—Hydroscience and Engineering, The Univ. of Iowa, Iowa City, IA 52242-1527. E-mail: ching-long-lin@uiowa.edu 3Professor, Dept. of Mechanical and Industrial Engineering, and IIHR—Hydroscience and Engineering, The Univ. of Iowa, Iowa City, IA 52242-1527. E-mail: v-c-patel@uiowa.edu |
| Abstract: | Turbulent open-channel flow over a two-dimensional dune is studied using an established large-eddy simulation code. The free surface is approximated as a shear free boundary. Turbulence statistics and instantaneous flow structures are examined. Numerical results from two computational grids agree with each other, and are also in good agreement with recently obtained experimental data. The mean velocity profiles show significant changes along the dune and there is no region that conforms to the standard law-of-the-wall. Profiles of the Reynolds stresses show distinct peaks marking the shear layer that originates from flow separation at the dune crest. Secondary peaks found further from the dune are ascribed to the shear layer over the upstream dune. Details of the separated flow and development of the flow after reattachment are well predicted. Quadrant analysis of the Reynolds shear stress shows that turbulent ejections dominate the near-wall motions. Complex water surface flow structures are visualized. |
| Keywords: | Dunes Open channels Turbulent flow Computation Simulation |