Buoyancy- to inertial-range transition in forced stratified turbulence

The buoyancy range, which represents a transition from large-scale wave-dom inated motions to small-scale turbulence in the oceans and the atmosphere, is investigated through large-eddy simulations. The model presented here us es a continual forcing based on large-scale standing internal waves and has a spectral truncation in the isotropic inertial range. Evidence is present ed for a break in the energy spectra from the anisotropic k(-3) buoyancy ra nge to the small-scale k(-5/3) isotropic inertial range. Density structures that form during wave breaking and periods of high strain rate are analyse d. Elongated vertical structures produced during periods of strong strainin g motion are found to collapse in the subsequent vertically compressional p hase of the strain resulting in a zone or patch of mixed fluid.