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Water Science and Engineering 2009, 2(3) 13-26  DOI:   10.3882/j.issn.1674-2370.2009.03.002   ISSN: 1674-2370 CN: 32-1785/TV

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hybrid LES-RANS modelzz')" href="#">hybrid LES-RANS model
open-channel flow
turbulence modeling
Cheng ZENG
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3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows

Jie ZHOU1, Cheng ZENG*2

1. College of Environmental Science and Engineering, Hohai University, Nanjing 210098, P. R. China
2. Department of Civil and Structural Engineering, Hong Kong Polytechnic University,
Hong Kong, P. R. China


The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage. To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows, a hybrid LES-RANS model, which combines the large eddy simulation (LES) model with the Reynolds-averaged Navier-Stokes (RANS) model, is proposed in the present study. The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel, as well as the downstream region of a branch channel. The LES model was used to simulate the channel diversion region, where turbulent flow characteristics are complicated. Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence. A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations. This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions. Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows

Keywordshybrid LES-RANS modelzz')" href="#"> hybrid LES-RANS model   open-channel flow   T-diversion   turbulence modeling  
Received 2009-08-06 Revised 2009-09-08 Online:  
DOI: 10.3882/j.issn.1674-2370.2009.03.002
Corresponding Authors: Jie ZHOU
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