2016/04/30 by Yong Liang, Y. Liang, Ahmad Zareei +2 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · #Acoustics #Atomic physics #Classical mechanics #Gravitational wave #Gravity wave #Harmonic #Harmonics #Instability #Internal wave #Mechanics #Ocean Waves and Remote Sensing #Oceanographic and Atmospheric Processes #Physics #Quantum mechanics #Resonance (particle physics) #Tropical and Extratropical Cyclones Research #physics.flu-dyn
paper · pdf · doi:10.1017/jfm.2016.754
arxiv created 2016/07/29 · openalex publication_date 2016/12/13 · arxiv updated 2017/03/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Here we show that there exist internal gravity waves that are inherently unstable, that is, they cannot exist in nature for a long time. The instability mechanism is a one-way (irreversible) harmonic-generation resonance that permanently transfers the energy of an internal wave to its higher harmonics. We show that, in fact, there are a countably infinite number of such unstable waves. For the harmonic-generation resonance to take place, the nonlinear terms in the free surface boundary condition play a pivotal role, and the instability does not occur in a linearly stratified fluid if a simplified boundary condition, such as a rigid lid or a linearized boundary condition, is employed. Harmonic-generation resonance presented here provides a mechanism for the transfer of internal wave energy to the higher-frequency part of the spectrum hence affecting, potentially significantly, the evolution of the internal waves spectrum.