SCALING LAWS IN WEAK TURBULENCE

Photon Homodyne Spectroscopy (HCS) and Laser Doppler Velocimetry (LDV) have been used to study turbulent velocity fluctuations V(R) associated with eddies of size R. For small R both types of measurement were consistent with a model in which the active regions of turbulence He on a fractal of dimension D, with D increasing from ~ 2 to ~ 3 as the Reynolds number (Re) increases above some threshold value. At larger eddy sizes, the LDV measurements show a different scaling of the velocity fluctuations. We associate these larger eddies with the energy reservoir that feeds the inertial cascade.