Laboratory evidence of three-dimensional frequency downshift of waves in along 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 tr ansverse standing waves can reach a similar level as that of the collinear waves, and a significant downshift is observed for the transverse waves. Di ssipation may be less important for the downshift than previously anticipat ed. (C) 1999 American Institute of Physics. [S1070-6631(99)02001-2].