A comparison of measured velocity structure functions and energy dissipation theories in turbulent flows

Parallel hot-wire sensors have been used to determine the structure functions of turbulence velocity fluctuations of up to 18th order, on the axis of a modified air jet, at Reynolds numbers of 72 and 102. Measured values of the exponent due to intermittency were compared with those predicted by the log-normal beta-model as well as a novel theory based on gamma statistics for the local average dissipation rate. The intermittency parameter, which appears as an exponent in the sixth-order structure function, is found to equal 0.2, in keeping with recently reported measurements.