CFD Online Discussion Forums - Molecular viscosity calculation in LES on OpenFOAM

Dear Foamers

I am working on a custom-code in OpenFOAM (libOpenSmoke). In this code, I have written the definition of the scalar dissipation rate in LES which includes molecular viscosity. The following is the formulation that I have used: In this formulation, turbulence->mu() refers to molecular viscosity, sigmat refers to laminar Schmidt number and Z is mixture fraction.

Code:

chi_st=2 * (turbulence->mu()/(rho*sigmat)) * magSqr(fvc::grad(Z));

I need to know that how does the “molecular viscosity” computes using LES filtering in OpenFOAM?
In literature, typically the filtered molecular viscosity is assumed to be a function of filtered temperature following a power law where the subgrid fluctuations of the temperature are neglected.

Would somebody PLZ hint me that which formulation is used in LES of OpenFOAM for calculating the filtered molecular viscosity?

Regards
Bobi