Two output fields have been added to help you in the estimation of resolution quality in a scale-resolving simulation of a turbulent flow. LES Resolution Estimate, in the Turbulence… category, is intended to be visualized in a preliminary RANS simulation, which will later be continued using a scale-resolving model. The value of this field is equal to the ratio of the local turbulence length scale, obtained in the RANS simulation, to the local mesh cell size. Mesh regions, where this value is equal to or higher than 5, may be considered as sufficiently refined for a scale-resolving simulation. This preliminary estimation of mesh resolution quality relies on the assumption that the RANS solution correctly represents the time-averaged properties of a considered turbulent flow.

Another output field, LES Resolution Quality, in the Unsteady Statistics… category, becomes available when time statistics are computed during a scale-resolving simulation. This field characterizes the achieved resolution quality as the resolved portion of the turbulence kinetic energy:

(10–15)

where the resolved kinetic energy is directly computed from the mean square velocity fluctuations

(10–16)

and the time-averaged modeled subgrid-scale kinetic energy is evaluated based on the subgrid-scale eddy viscosity , density , and strain rate magnitude :

(10–17)

A LES Resolution Quality that is 0.8 or higher normally indicates a sufficiently resolved turbulent flow solution.

In the current beta feature status, these two output fields are not yet available with all models. For example, the first field, LES Resolution Estimate, is not available with the Spalart-Allmaras model.