Internal gravity waves in stratified flows with and without vortical modes

We analyze direct numerical simulations of stratified turbulence without shear modes, and with or without vortical modes at various Froude and buoyancy Reynolds numbers. It allows us to investigate the effects of vortical modes on the dynamics of stratified flows. A spatiotemporal analysis reveals slow internal gravity waves interacting by triadic resonance instabilities in our strongly stratified flow simulations such as the one in the figure. We observe that removing vortical modes helps to concentrate the energy around the wave frequency, but it is not enough to observe a weak internal gravity wave's turbulence regime.