This sets the absolute pressure level that all other relative pressure set in a simulation are measured relative to. For details, see Setting a Reference Pressure in the CFX-Solver Modeling Guide.
This model selection depends upon the type of fluid you have chosen. For details, see Heat Transfer in the CFX-Solver Modeling Guide.
The models available depend upon the fluid that has been chosen. For details, see Turbulence and Near-Wall Modeling in the CFX-Solver Modeling Guide.