EXPERIMENTAL-STUDY OF LONG NONLINEAR INTERNAL WAVES IN ROTATING FLUID

Experiments were performed on the rotating platform 14 m in diameter e quipped with a simple internal wave generator. Internal waves were gen erated for a wide range of Coriolis parameters. When the rotation is v ery weak, i.e., when the internal Rossby radius of deformation is much larger than the wavelength, then the stable nonlinear waves generated are solitary waves. These have a horizontal crest, as in the nonrotat ing case. When the rotation is strong, i.e,. when the internal Rossby radius is at most comparable with the wavelength, then Sverdrup-like p eriodic waves can be generated, but no solitary wave can then propagat e. Their phase speed increases with increasing amplitude. Then, there are two characteristic wave lengths: one which varies with the inverse square root of the amplitude, as for the KdV wave, and the other, lin ked with the rotation, which varies as the square root of the amplitud e. The experimental results are thus in agreement with most of the con clusions in recent analytical developments.