## 12.3.2 Transport Equation for the Spalart-Allmaras Model

The transported variable in the Spalart-Allmaras model, , is identical to the turbulent kinematic viscosity except in the near-wall (viscous-affected) region. The transport equation for is

 (12.3-1)

where is the production of turbulent viscosity and is the destruction of turbulent viscosity that occurs in the near-wall region due to wall blocking and viscous damping. and are constants and is the molecular kinematic viscosity. is a user-defined source term. Note that since the turbulence kinetic energy is not calculated in the Spalart-Allmaras model, the last term in Equation  12.2-5 is ignored when estimating the Reynolds stresses.

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