Large eddy simulations of decaying rotating turbulence

Abstract

Large eddy simulations of homogeneous isotropic turbulence subjected to system rotation were performed using the truncated Navier-Stokes method. In the method the Navier-Stokes equations are solved through a sequence of direct numerical simulation runs and a periodic processing of small scales to provide the necessary dissipation. The method is evaluated by comparing simulation results with theoretical analysis, direct numerical simulations, as well as with other large eddy simulation results. Obtained results demonstrate several advantages of the method over traditional large eddy simulations models. The method captures important features of rotating turbulence: the energy decay is inhibited, the energy spectrum departs from the classical k−5/3 form, and initially isotropic turbulence becomes anisotropic. For increasing rotation rate three distinct regimes are observed. At low rotation rates, the influence of rotation is weak and flow behaves like for nonrotating cases. At intermediate rotation rates strong coupling between rotation and nonlinear interactions has a significant influence on turbulence. At high rotation rates viscous effects dominate over nonlinear effects. Furthermore, for high Reynolds numbers, small Rossby numbers, and large elapsed time, the k−3 energy spectrum is observed due to the anisotropy identified by various indicators, rather than the k−2 form found under the assumption of isotropy.