ASA 124th Meeting New Orleans 1992 October

3aPA9. Experiments on capillary wave turbulence.

William Wright

Robert Hiller

Seth Putterman

Phys. Dept., Univ. of California, Los Angeles, CA 90024

Measurements of the response of a fluid surface to parametric excitation at a frequency that excites ripples, displays a number of qualitatively distinct regimes. As the amplitude is increased, standing waves (with higher harmonics) turn into a stationary, square ``crystal,'' pattern. At higher amplitudes, ``dislocations'' migrate through the pattern. While at the highest amplitudes, the spectrum becomes broadband with no discernable spatial pattern. Measurements are being made with a thin wire probe as well as the shadowgraph technique. The wire indicates that the broadband spectrum follows a power law: and the surface FFT indicates that many modes participate in the motion. Improvements in this absolute calibration are required before one can determine whether wave turbulence has been observed. [Work supported by the US DOE Division of Engineering and Geophysics and NASA---Microgravity.]