Fluid turbulence is commonly modeled by the Navier-Stokes equations with a large Reynolds number. The simulation of turbulence model is known to be very difficult. We study artificial spectral viscosity models that render the simulation of turbulence tractable. The models introduce several parameters. We show that the models have solutions that converge, in certain parameter limits, to solution...

In a recent work, the effects of nonlinear self-consistent profile relaxation on the ITG turbulence in global delta-f particle simulations were studied [1] using Gyrokinetic Toroidal Code (GTC) [2]. In contrast to several other gyrokinetic turbulence models, GTC shows that the turbulence is insensitive to minute or drastic profile changes and reaches the similar flux levels irrespective of whet...

The non linear eddy viscosity models are good candidates for the simulation of turbulent flows of industrial interest. In fact these models allow to avoid the complexity of the second-order closure models, and to capture more physics than the classical two equation turbulence models based on the Boussinesq hypothesis. Non linear κ-ε turbulence models have been developed by the authors, in the f...

Context. Supersonic turbulence in molecular clouds is a dominant agent that strongly affects the clouds’ evolution and star formation activity. Turbulence may be initiated and maintained by a number of processes, acting at a wide range of physical scales. By examining the dynamical state of molecular clouds, it is possible to assess the primary candidates for how the turbulent energy is injecte...