New expressions for the surface roughness length and displacement height in the atmospheric boundary layer
Lin Jian-Zhong(林建忠)a)b)†, Li Hui-Jun(李惠君)a), and Zhang Kai(张凯)a)
a State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, China; b China Jiliang University, Hangzhou 310018, China
Abstract An alternative model for the prediction of surface roughness length is developed. In the model a new factor is introduced to compensate for the effects of wake diffusion and interactions between the wake and roughness obstacles. The experiments are carried out by the use of the hot wire anemometry in the simulated atmospheric boundary layer in a wind tunnel. Based on the experimental data, a new expression for the zero-plane displacement height is proposed for the square arrays of roughness elements, which highlights the influence of free-stream speed on the roughness length. It appears that the displacement height increases with the wind speed while the surface roughness length decreases with Reynolds number increasing. It is shown that the calculation results based on the new expressions are in reasonable agreement with the experimental data.
Received: 07 October 2006
Revised: 18 January 2007
Accepted manuscript online:
Fund: Project supported by
the Major Program of the National Natural Science Foundation of
China (Grant No 10632070).
Cite this article:
Lin Jian-Zhong(林建忠), Li Hui-Jun(李惠君), and Zhang Kai(张凯) New expressions for the surface roughness length and displacement height in the atmospheric boundary layer 2007 Chinese Physics 16 2033
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