Subgrid

When using LES, the time-dependent three-dimensional momentum and continuity are solved for. A subgrid turbulence model is used to mode the turbulent scales that are smaller than the cells. Instead of the traditional time averaging, the equations for using LES are filtered in space, and is a function of space and time. 

David.son, L, Large eddy simulation A dynamic one-equation subgrid model for three-dimensional recirculating flow. In llth Int. Symp. on Turbulent Shear Flow, vol. 3, pp. 26.1-26.6, Grenoble, 1997. 

Bonan, G. B. (1996c). Sensitivity of a GCM simulation to subgrid infiltration and surface runoff, Clim. Dyn. 12,279-285. 

The ability to resolve the dissipation structures allows a more detailed understanding of the interactions between turbulent flows and flame chemistry. This information on spectra, length scales, and the structure of small-scale turbulence in flames is also relevant to computational combustion models. For example, information on the locally measured values of the Batchelor scale and the dissipation-layer thickness can be used to design grids for large-eddy simulation (LES) or evaluate the relative resolution of LES resulfs. There is also the potential to use high-resolution dissipation measurements to evaluate subgrid-scale models for LES. 

We should note that expressions (2.21) and (2.27) were obtained in application to a specific bridge of the open type characterized by thickness h and initial concentration of superstoichiometric metal [Me ]o- In real polycrystal with dominant fraction of bridges of this very type there is a substantial spread with respect to the thickness of bridges and to concentration of defects. Therefore, the local electric conductivity of the material in question is a random value of statistical ohmic subgrid formed by barrier-free contacts of microoystals. 

Tompkins A (2002) A prognostic parameterization for the subgrid-scale variability of water vapor and clouds in large-scale models and its use to diagnose cloud cover. J Atmos Sci 59 1917-1942 Turusov V, Rakitsky V, Tomatis L (2002) Dichlorodiphenyltrichloroethane (DDT) ubiquity, persistence, and risks. Environmental Health Perspectives 101 125-128 UNEP (2001) Stockholm convention on persistent organic pollutants. http //chmpopsint/... 

It is then assumed that due to this separation in scales, the so-called subgrid scale (SGS) modeling is largely geometry independent because of the universal behavior of turbulence at the small scales. The SGS eddies are therefore more close to the ideal concept of isotropy (according to which the intensity of the fluctuations and their length scale are independent of direction) and, hence, are more susceptible to the application of Boussinesq s concept of turbulent viscosity (see page 163). 

Cook, A. W. and J. J. Riley (1994). A subgrid model for equilibrium chemistry in turbulent flows. Physics of Fluids 6, 2868-2870. 

Subgrid-scale modeling for turbulent reacting flows. Combustion and Flame 112, 593-606. 

Large eddy simulation of a nonpremixed reacting jet Application and assessment of subgrid-scale combustion models. Physics of Fluids 10, 2298-2314. 

Eidson, T. M. (1985). Numerical simulation of the turbulent Rayleigh-Benard problem using subgrid modelling. Journal of Fluid Mechanics 158, 245-268. 

Germano, M., U. Piomelli, P. Moin, and W. H. Cabot (1991). A dynamic subgrid-scale eddy viscosity model. Physics of Fluids 7, 1760-1765. 

Jimenez, J., A. Linan, M. M. Rogers, and F. J. Higuera (1997). A priori testing of subgrid models for chemically reacting non-premixed turbulent flows. Journal of Fluid Mechanics 349, 149-171. 

One-dimensional turbulence A new approach to high-fidelity subgrid closure of turbulent flow simulations. Computer Physics Communications 148, 1-16. 

Meneveau, C., T. S. Lund, and W. Cabot (1996). A Lagrangian dynamic subgrid-scale model of turbulence. Journal of Fluid Mechanics 319, 353-385. 

Wall, C., B. J. Boersma, and R Moin (2000). An evaluation of the assumed beta probability density function subgrid-scale model for large eddy simulation of nonpremixed, turbulent combustion with heat release. Physics of Fluids 12, 2522-2529. 

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