As mentioned above, the flow solver also requires that you supply the ideal gas specific heat capacity coefficients. These coefficients allow the flow solver to calculate the specific heat capacity as a function of both temperature and pressure. The Real Gas Zero Pressure Coefficients option is used for this purpose and is described in the modeling documentation. For details, see Real Gas.

When running this equation of state it is highly recommended that you select the Rigid Non Interacting Sphere or Interacting Sphere Model for dynamic viscosity and the Modified Eucken Model for thermal conductivity.

The use of the Redlich Kwong cubic state equation model for flows of almost entirely pure liquid (eg: single phase liquid problem, boiling, cavitation) is highly discouraged. If you want to use one of the cubic equations of state for this type of problem then you should use the Peng Robinson equation of state instead, which, by default will force the liquid phase properties to be dependent on temperature and pressure fully consistent with that equation of state.