Entropy, Closures and Subgrid Modeling

Entropy, Closures and Subgrid Modeling

Maximum entropy states or statistical mechanical equilibrium solutions have played an important role in the development of a fundamental understanding of turbulence and its role in geophysical flows. In modern general circulation models of the earth’s atmosphere and oceans most parameterizations of the subgrid-scale energy and enstrophy transfers are based on ad hoc methods or ideas developed f...

Statistical Dynamical Closures and Subgrid Modeling for Inhomogeneous QG and 3D Turbulence

Statistical dynamical closures for inhomogeneous turbulence described by multi-field equations are derived based on renormalized perturbation theory. Generalizations of the computationally tractable quasi-diagonal direct interaction approximation for inhomogeneous barotropic turbulent flows over topography are developed. Statistical closures are also formulated for large eddy simulations includ...

Dynamic Computational Subgrid Modeling I

In this paper we propose and study a subgrid model for linear convection-diiusion-reaction problems with fractal rough coeecients. The subgrid model is based on extrapolation of a modeling residual from coarser scales using a computed solution on a nest scale as reference. We show in experiments that a solution with subgrid model on a scale h in most cases corresponds to a solution without subg...

Modeling Subgrid Viscosity for Advection-Diffusion Problems

Matrix exponential-based closures for the turbulent subgrid-scale stress tensor.

Two approaches for closing the turbulence subgrid-scale stress tensor in terms of matrix exponentials are introduced and compared. The first approach is based on a formal solution of the stress transport equation in which the production terms can be integrated exactly in terms of matrix exponentials. This formal solution of the subgrid-scale stress transport equation is shown to be useful to ex...