Location

Utah State University

Start Date

10-5-2010 1:45 PM

Description

Internal gravity waves are inherent in the atmosphere and ocean as a result of the stable stratification of these mediums. Internal waves may be generated in many ways, including by flow over topography, convective storms, or turbulent mixing. As they propagate through their medium, internal waves of various scales (tens of meters to tens of kilometers) interact with other fluid flow phenomena found throughout geophysical fluid flows. The interaction of small-scale internal waves with a vortex dipole is of particular interest due to the rotation of the earth resulting in constant vortex generation. The speed and direction with which internal waves approach a vortex dipole can significantly affect the wave-vortex interaction, determining if the energy of the internal waves will be absorbed, refracted, or unaffected by the dipole. The interaction presented involves waves propagating in the same direction as the translation of the dipole. This co-propagating interaction yields a spreading of wave energy, termed defocusing, observed as rays interact with the dipole and then diverge in the spanwise direction. Waves can approach critical levels, where the wave energy is absorbed by the dipole or the waves are overturned and possibly break. As wave breaking cannot be simulated with this linear model, an analysis of changes in wave steepness aids in estimating the onset of breaking. The numerical results support the experimental study of Godoy-Diana, Chomaz and Donnadieu (2006).

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May 10th, 1:45 PM

Numerical Investigation of Internal Wave-Vortex Interactions

Utah State University

Internal gravity waves are inherent in the atmosphere and ocean as a result of the stable stratification of these mediums. Internal waves may be generated in many ways, including by flow over topography, convective storms, or turbulent mixing. As they propagate through their medium, internal waves of various scales (tens of meters to tens of kilometers) interact with other fluid flow phenomena found throughout geophysical fluid flows. The interaction of small-scale internal waves with a vortex dipole is of particular interest due to the rotation of the earth resulting in constant vortex generation. The speed and direction with which internal waves approach a vortex dipole can significantly affect the wave-vortex interaction, determining if the energy of the internal waves will be absorbed, refracted, or unaffected by the dipole. The interaction presented involves waves propagating in the same direction as the translation of the dipole. This co-propagating interaction yields a spreading of wave energy, termed defocusing, observed as rays interact with the dipole and then diverge in the spanwise direction. Waves can approach critical levels, where the wave energy is absorbed by the dipole or the waves are overturned and possibly break. As wave breaking cannot be simulated with this linear model, an analysis of changes in wave steepness aids in estimating the onset of breaking. The numerical results support the experimental study of Godoy-Diana, Chomaz and Donnadieu (2006).