Laboratory evidence of three-dimensional frequency downshift of waves in a long tank

Experiments show that the evolution of Stokes waves can lead to significant growth of transverse standing wave oscillations across the tank at a large distance from the wave maker. The peak power intensity of narrow-banded transverse standing waves can reach a similar level as that of the collinear waves, and a significant downshift is observed for the transverse waves. Dissipation may be less important for the downshift than previously anticipated. (C) 1999 American Institute of Physics. [S1070-6631(99)02001-2].