PROBABILITY DENSITY OF VELOCITY INCREMENTS IN WEAKLY TURBULENT PIPE-FLOW

New Laser Doppler Velocimetry measurements are presented of the probab ility density function of velocity increments for pipe flow at very lo w Reynolds number. It will be shown that stretched exponentials provid e a good model to the tails of the density function. This result paral lels that already known for fully developed turbulence and gains furth er experimental evidence to the concept of extended self-similarity fo r very low Reynolds number.