Using cavitation to measure statistics of low-pressure events in large-Reynolds-number turbulence

The structure of the pressure field of a turbulent water flow between count er-rotating disks is studied using cavitation. The flow is seeded with micr oscopic gas bubbles and the hydrostatic pressure is reduced until large neg ative pressure fluctuations trigger cavitation. Cavitation is detected via light scattering from cavitating bubbles. The spatial structure of the low- pressure events are visualized using a high-speed video system. A fast phot o detector is used to measure the scaling of the cavitation statistics with the pressure. This data is used to determine the shape of the tail of the probability density function for the pressure. The tail is found to be expo nential and scales more rapidly with Reynolds number than the standard devi ation of the pressure. This may indicate the influence of internal intermit tency. (C) 2000 American Institute of Physics. [S1070-6631(00)01106-5].