  The results of large eddy simulation (LES) using three sub-grid scale models,
namely: constant coefficient Smagorinsky, dynamic Smagorinsky, and a dynamic
Clark model, for rotating stratified turbulence in the absence of forcing using
large-scale isotropic initial condition, are reported here. The LES results are
compared to in-house direct numerical simulation (DNS) for establishing
grid-independence requirements. Three cases with varying ratios of
Brunt-Vaisala frequency to the inertial wave frequency, N / f, have been chosen
to evaluate the performance of LES models. The Reynolds number and N / f are
chosen as (a) Case 1: Re = 3704, N / f = 5, (b) Case 2: Re = 6667, N / f = 40,
and, (c) Case 3: Re = 6667, N / f = 138. This framework is used to illustrate
the relative magnitudes of the stratification and rotation which is observed in
geophysical flows. Various quantities including turbulent kinetic energy (tke),
turbulent potential energy (tpe), total dissipation, potential and total energy
spectra, and their fluxes, are analyzed to understand the predictive capability
of the various LES models. Results show that all the SGS model predictions are
very similar, with the classical Smagorinsky model displaying the highest
deviation compared to DNS. The effect of an increase in the value of N / f is
also seen in the results of LES with an increase in the oscillations observed
in the evolution of tke and tpe and a reduction in dissipation. The spectral
analysis shows that the dynamic Clark and Smagorinsky models predict the
large-scale physics (\kappa < 10), while the small scales (10 < \kappa < 64)
energy is under-predicted.
