Numerical investigation of internal wave-vortex interactions

Internal gravity waves are inherent in the atmosphere due to its stable stratification. They may be generated in many ways, including by flow over topography, convective storms, or turbulent mixing. As they propagate through the atmosphere, internal waves of various scales (tens of meters to tens of kilometers) interact with various 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. Variations of this interaction are investigated through three-dimensional linear and nonlinear numerical simulations. The linear theory is ideal due to the speed of calculations: tens of thousands of waves can be tested in a few hours using a standard PC. Physical dynamics of possible interactions are quantified through the calculations of basic wave parameters and amplitudes. Fully nonlinear simulations and experimental results are used to validate the linear theory.