剪切湍流中的湍动扩散系数及弥散系数

本文通过对湍动扩散及纵向弥散成因的分析,确定在湍流扩散中起主要作用的是湍流涡体的湍动,而在纵向弥散过程中起主要作用的是断面上时均流速分布不均匀。从此观点出发,通过雷诺比拟等假设,导出了指数流速分布下的弥散系数表达式,并且分析了指数n、u_*/U等因素对弥散系数的影响。最后从湍流结构试验,验证了所导出的弥散系数表达式的正确性。

Turbulent Diffusion Coefficient and Dispersion in Shear Turbulent Flows

In this paper, the assumptions that the main affecting factor on the turbulent diffusion is the turbulent motion of turbulence eddies and the main affecting factor on the dispersion process is the non-uniform velocity profile are confirmed through the analysis of the contributing factors of turbulent diffusion and of longitudinal dispersion.The expression of the dispersion coefficient, under the condition of exponential velocity profile, is derived and the effects of index number and u*/V on dispersion coefficient are analysed.The experiments of the turbulence structure are carried out and the correctness of the derived formulation of the dispersion coefficient is verified through the experiments.