Constrained large-eddy simulation of turbulent flow over inhomogeneous rough surfaces |
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Authors: | Wen Zhang Minping Wan Zhenhua Xia Jianchun Wang Xiyun Lu Shiyi Chen |
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Institution: | 1. Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, China;2. Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China;3. Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China;4. Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026, China |
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Abstract: | In this work we extend the method of the constrained large-eddy simulation(CLES) to simulate the turbulent flow over inhomogeneous rough walls. In the original concept of CLES, the subgrid-scale(SGS) stress is constrained so that the mean part and the fluctuation part of the SGS stress can be modelled separately to improve the accuracy of the simulation result. Here in the simulation of the rough-wall flows, we propose to interpret the extra stress terms in the CLES formulation as the roughness-induced stress so that the roughness inhomogeneity can be incorporated by modifying the formulation of the constrained SGS stress. This is examined with the simulations of the channel flow with the spanwise alternating high/low roughness strips. Then the CLES method is employed to investigate the temporal response of the turbulence to the change of the wall condition from rough to smooth. We demonstrate that the temporal development of the internal boundary layer is just similar to that in a spatial rough-tosmooth transition process, and the spanwise roughness inhomogeneity has little impact on the transition process. |
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