Turbulence level measurement by speckle velocimetry

Speckle particle-imaging velocimetry is of interest in experimental flow studies due to the capability for simultaneous study of large flow fields that it offers. Attention is given to the results of the first application of this technique, in which the degree of turbulence is obtained for a wind tunnel flow. Assuming a gaussian density function for the velocity, the degree of turbulence was calculated from the width of Gaussian fits to the experimental data employing the Fourier transform relation between visibility and density functions. A comparison is made of the results thus obtained with those from hot wire measurements. (O.C.)