Instability and Resonance

Internal waves occur in the interior of a fluid and are caused by density stratification. A slight change in liquid density, which occurs often in the ocean, causes significantly large internal waves. Moreover, internal waves play an essential role in weather condition, mixing, and circulation in the ocean through their breaking. The energy transport mechanism is currently not well understood. In my prior research, we identified a second-harmonic instability mechanism which describes the transfer of internal wave energy to higher frequencies. This instability offers a new potential mechanism for energy transfer to higher modes that results in wave breaking. We furthermore characterized the way in which internal waves in ocean interact with the sea-bed through Bragg resonance which potentially explains experimentally observed areas of high-mixing within the ocean.

Publications:

• F. Karimpour, A. Zareei, J. Choufag & M.-R. Alam Sensitivity of internal wave energy distribution over seabed corrugations to adjacent seabed feature , Journal of Fluid Mechanics, 824, pp 74-96, [PDF, arXiv]
• Y. Liang, A. Zareei & M.-R. Alam, Inherently unstable internal gravity waves due to resonant harmonic generation, Journal of Fluid Mechanics, 811 (2017): 400-420, [PDF]