The Generation of Harmonic Waves in Periodic, Interfacial Wave Interactions with a Submerged Ridge

When two-layer, periodic, interfacial wave trains pass over a Gaussian ridge, waves of higher harmonic frequency can be generated at the ridge, which then propagate downstream independently of the incident wave. In laboratory experiments, the amount of energy transferred to higher harmonics scales with the non- linearity of the main wave over the ridge crest. The length scale of the obstacle relative to the wavelength can also influence the energy transfer. The stratification sets upper limit on which harmonic frequencies can be excited. This wave-topography interaction provides a possible mechanism for transferring energy in the internal wave field to smaller scales.