Publication: Stratified turbulence at the buoyancy scale
All || By Area || By Year| Title | Stratified turbulence at the buoyancy scale | Authors/Editors* | M. L. Waite |
|---|---|
| Where published* | Phys. Fluids |
| How published* | Journal |
| Year* | 2011 |
| Volume | 23 |
| Number | |
| Pages | 066602 |
| Publisher | |
| Keywords | |
| Link | http://pof.aip.org/resource/1/phfle6/v23/i6/p066602_s1 |
| Abstract |
Numerical simulations of forced stratified turbulence are presented, and the dependence on horizontal resolution and grid aspect ratio is investigated. Simulations are designed to model the small-scale end of the atmospheric mesoscale and oceanic submesoscale, for which high horizontal resolution is usually not feasible in large-scale geophysical fluid simulations. Coarse horizontal resolution, which necessitates the use of thin grid aspect ratio, yields a downscale stratified turbulence energy cascade in agreement with previous results. We show that with increasing horizontal resolution, a transition emerges at the buoyancy scale 2PiU/N, where U is the rms velocity and N is the BruntâVaisala frequency. Simulations with high horizontal resolution and isotropic grid spacing exhibit a spectral break at this scale, below which there is a net injection of kinetic energy by nonlinear interactions with the large-scale flow. We argue that these results are consistent with a direct transfer of energy to the buoyancy scale by KelvinâHelmholtz instability of the large-scale vortices. These findings suggest the existence of a distinct subrange of stratified turbulence between the buoyancy and Ozmidov scales. This range must be at least partially resolved or parameterized to obtain robust simulations of larger-scale turbulence. |
Back to page 7 of list