The Spalart-Allmaras-Model is a one-equation-model. It describes the transport of the turbulent viscosity. Why do I have to specify two values at an inlet for the option ‘TI and eddy viscosity ratio’. Answers: The S-A-Model is still in Beta-Stadium in CFX. Hence, the GUI is not consistent for that turbulence model. For this particular boundary condition, the value of TI is simply ignored. The other options require two values to calculate the turbulent viscosity nu_t at the inlet: Intensity and Length Scale: nu_t = Cmu * sqrt(k) * length_scale, k = 1.5 * Intensity^2 * Velocity^2 k and epsilon: nu_t = Cmu * k^2 / epsilon k and omega: nu_t = k / omega k and Length Scale: nu_t = Cmu * sqrt(k) * length_scale