The Zero Equation model implemented in CFX is simple to implement and use, can produce approximate results very quickly, and provides a good initial guess for simulations using more advanced turbulence models. In CFX, a constant turbulent eddy viscosity is calculated for the entire flow domain. If you specify an eddy viscosity, this value is used instead of the solver calculated value. You should not use this model to obtain final results. For details, see The Zero Equation Model in Ansys CFX in the CFX-Solver Theory Guide.