Be aware of the density and specific heat dependencies.
For a pure substance, the flow solver allows only density and specific heat capacity to be functions of temperature or pressure.
When you select the Value option for density or specific heat capacity, you can use an expression to specify Density and/or Specific Heat Capacity, but the expression is allowed to depend only on pressure and temperature for liquids and gases. For a solid, they can depend on temperature or spatial location (x, y, z), but not both at the same time.
For ideal gases, the density is evaluated using the Ideal Gas law and the specific heat may be a function of temperature only.
Both density and specific heat capacity can also be a function of an algebraic Additional Variable, but the algebraic Additional Variable must be a function only of temperature and pressure. CFX-Pre will not allow you to set this and you must therefore edit the CCL file to implement such a case.
If density, specific heat, or other properties are set as expressions that depend on pressure, the solver automatically uses the absolute pressure when evaluating the expression.