Required field
Required field
Required field
Required field

# nuTilda

nuTilda ($$\tilde{\nu}$$) is a viscosity-equivalent variable required to be defined as a boundary condition while using the LES Spalart-Allmaras turbulence model. Spalart-Allmaras is an LES (Large Eddy Simulation) based model that solves for the transport of nuTilda. $$\tilde{\nu}$$ is also referred to as Spalart-Allmaras variable.

nuTilda is not explicitly available in the list of boundary conditions and needs to be defined under Custom boundary condition in units of $$m^2/s$$ or $$(lbf.s.in)/lb$$.

Based on the chosen analysis type and simulation settings, the following options are available to define nuTilda:

• Calculated
• Symmetry
• Fixed value
• Inlet-outlet
• Wall function
• Full resolution

Note

In CFD simulations using LES models, turbulence variables at walls are defined as a fixed value of zero or zero gradient. This is only valid if the velocity at the wall is zero, i.e., no oscillations and therefore no turbulence.

Following is a snap from the workbench showing the Custom boundary condition utility:

Last updated: June 14th, 2021