Fields Institute Workshop on Nonlinear Wave Dynamics

Carleton University, August 20-22 2008


Triantaphyllos R. Akylas

Department of Mechanical Engineering, Massachusetts Institute of Technology

Internal gravity waves in continuously stratified fluids

Lecture I: Internal waves in continuously stratified fluids
A survey of the governing equations and basic properties of internal gravity waves in continuously stratified fluids. Geophysical significance of internal waves in the oceans and atmosphere.

Lecture II: Nonlinear internal gravity wave beams
Internal gravity waves are anisotropic since gravity provides a preferred direction. As a result, the response to localized time-harmonic forcing features, rather than circular wavefronts, beam-like disturbances propagating along specific directions depending on the driving frequency. Recent advances in understanding the propagation and nonlinear interactions of finite-amplitude wave beams will be discussed.

Lecture III: Reflecting tidal wave beams and local generation of solitary waves in the ocean thermocline.
A nonlinear long-wave model will be presented of how internal wave beams, that are induced by tidal flow over bottom topography and then reflect from the ocean thermocline at a significant distance from the continental shelf, may give rise to solitary waves. Comparison of the theoretical predictions against field observations will be made, supporting this local generation mechanism.