Instabilities of Internal Gravity Wave Beams

Parametric subharmonic instability of internal gravity wave beams

Internal gravity wave beams are time-harmonic plane waves with general spatial profile that arise in continuously stratified fluids owing to the anisotropy of this wave motion. In the last decade, these wave disturbances have been at the forefront of research, both from a fundamental perspective and in connection with various geophysical flow processes. Oceanic internal wave beams, in particula...

Three-dimensional Instability of Internal Gravity Wave Beams

Takeshi Kataoka and T. R. Akylas Department of Mechanical Engineering, Massachusetts Institute of Technology [email protected] Abstract The stability of isolated and interacting internal gravity wave beams to three-dimensional perturbations is studied, based on the beam–mean-flow interaction equations derived in Kataoka and Akylas (2015). These two-dimensional states are found to be unstable as ...

Limit states of internal wave beams

Visualization of nonlinear effects in reflecting internal wave beams

Recent theoretical and numerical investigations predict that localized nonlinear effects in the overlapping region of an incoming and reflected internal wave beam can radiate higher-harmonic beams. We present the first set of experimental visualizations, obtained using the digital Schlieren method, that confirm the existence of radiated higher-harmonic beams. For arrangements in which the angle...

Internal gravity wave radiation into weakly stratified fluid

It is shown by way of nonlinear numerical simulations of flow restricted to two dimensions that a compact wavepacket of large-amplitude internal gravity waves incident upon a weakly stratified region in which the buoyancy frequency is less than the frequency of the wavepacket may partially transmit energy into this region through the generation of a wavepacket of lower frequency. In part, the t...