Master's student Sean Smith created experiments to analyze two internal wave beams colliding. When these types of waves collide they create harmonic waves with frequencies of the sum or difference of the colliding wave frequencies. Sean was able to estimate the energy at which these waves will propagate away.
For videos of the resulting harmonics created see: http://youtu.be/rF_zWdWk52c
The paper submitted on this work can be found below. The abstract is included here:
Internal waves are abundant in both the ocean and atmosphere. However, nonlinear generation of harmonic waves due to interactions between internal waves have not been a major focus in previous research. When two nonresonant internal waves collide, harmonics are formed at the sum and difference of multiples of the colliding waves' frequencies, taking energy from the initial wave beams. Here we experimentally create interactions between nonresonant internal waves and determine a relative energy partition to second-harmonics for eight unique configurations. It is found that approximately 6% to $9% of the original relative energy of the two interacting waves is partitioned to harmonics. It is found that this value is more dependent on the relative direction of the colliding waves approach to each other than on their particular frequencies. The majority of the incoming energy from the colliding waves also leaves the interaction with the same frequency.