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Wind and Structures Volume 17, Number 4, October 2013 , pages 361-377 DOI: https://doi.org/10.12989/was.2013.17.4.361 |
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Developments and applications of a modified wall function for boundary layer flow simulations |
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Jian Zhang, Qingshan Yang and Q.S. Li
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| Abstract | ||
| Wall functions have been widely used in computational fluid dynamics (CFD) simulations and can save significant computational costs compared to other near-wall flow treatment strategies. However, most of the existing wall functions were based on the asymptotic characteristics of near-wall flow quantities, which are inapplicable in complex and non-equilibrium flows. A modified wall function is thus derived in this study based on flow over a plate at zero-pressure gradient, instead of on the basis of asymptotic formulations. Turbulent kinetic energy generation (GP), dissipation rate (e) and shear stress (tw) are composed together as the near-wall expressions. Performances of the modified wall function combined with the nonlinear realizable k -e turbulence model are investigated in homogeneous equilibrium atmosphere boundary layer (ABL) and flow around a 6 m cube. The computational results and associated comparisons to available full-scale measurements show a clear improvement over the standard wall function, especially in reproducing the boundary layer flow. It is demonstrated through the two case studies that the modified wall function is indeed adaptive and can yield accurate prediction results, in spite of its simplicity. | ||
| Key Words | ||
| wall function; k -e model; computational fluid dynamics (CFD); atmosphere boundary layer; bluff body | ||
| Address | ||
| Jian Zhang : School of Civil Engineering, Beijing Jiaotong University, Beijing, China; Department of Civil and Architectural Engineering, City University of Hong Kong, Hong Kong Qingshan Yang: School of Civil Engineering, Beijing Jiaotong University, Beijing, China Q.S. Li: Department of Civil and Architectural Engineering, City University of Hong Kong, Hong Kong | ||