On the directional dependence of turbulence properties in anisotropic turbulent flows

 An examination is made of the consequences of a zero correlation between fluctuations in velocity level and flow direction in a stationary anisotropic turbulent flow. This zero correlation results from the fact that in a stationary turbulent flow fluctuations in both velocity level and flow direction are entirely random processes. In this paper this is considered to be an inherent property of stationary flow and utilised to simplify both the computation and the measurement of anisotropic turbulence. This new method shows several advantages compared to earlier methods. First, the spatial distribution of the flow turbulence has been shown to be a trigonometric function of the spatial parameter. Second, the relationship between Reynolds normal and shear stresses has been established. Third, when a two-dimensional flow field is concerned, two measurements using a one-component LDA system are sufficient to identify the turbulence. Until now it has been considered that three such measurements were necessary. The feasibility of the method, known as zero correlation method, has been analysed and demonstrated by experiment. Received: 29 January 1997/Accepted: 30 July 1997