MEASUREMENTS OF TURBULENT VELOCITY FLUCTUATIONS IN A PLANAR COUETTE CELL

The anisotropy of turbulent velocity fluctuations in a planar Couette cell has been investigated by using homodyne photon correlation spectroscopy (HCS). We find that [delta v(q)(l)], the mean velocity difference between two points separated by a distance l, is consistent with the scaling behavior [delta v(q)(l)]proportional to l(0.55), These measurements were made at a Reynolds number Re much greater than Re-c, where the subcritical transition first occurs. The HCS technique was also used to measure Re-c itself. (C) 1995 American Institute of Physics.