SPATIAL RESOLUTION OF VORTICITY METER AND OTHER HOT-WIRE ARRAYS

Analyses of the spatial resolution of the Kovasznay vorticity meter and of arrays for measuring velocity derivatives in isotropic turbulence are presented. Pao's three-dimensional spectrum is used, allowing calculations of the measured values of the one-dimensional vorticity spectrum and mean-square velocity derivatives to be compared with their predicted values. It is found that for accurate measurement the array size should be of the order of the Kolmogorov microscale of the turbulence field.