### 1.4.6. Table Generation Pressure and Temperature Limits

If you have defined density or specific heat capacity as a function of pressure and/or temperature using a CEL expression, User Fortran, IAPWS or Redlich Kwong equation of state then the CFX-Solver will generate tables for properties. The default temperature range is 100 K to 3000 K and the default pressure range is 0.01 bar to 10 bar.

If this range is not appropriate for the operating conditions of your model you should consider setting appropriate temperature and pressure limits for property table generation. See the Materials details view in CFX-Pre and complete the Table Generation section. For details, see Material Properties Tab in the CFX-Pre User's Guide. The temperature limits specified should include enough range to convert the static temperature and total temperature range for your problem. Similarly, the pressure limits should be based on the minimum and maximum total pressure and static pressure expected in the simulation.

If the limits you enter are too narrow, then the CFX-Solver will clip properties at the bounds you have supplied. That being said though, you want to use the smallest range you can get away with because the more accurate the calculation of enthalpy will be, but the temperature and pressure in your simulation should not fall outside of the range specified.

Important: The minimum and maximum pressures are not entered relative to the reference pressure (as most other pressures in CFX are). They are entered as absolute values. This is because the reference pressure is a property of a particular CFD problem and not a generic property of the material. However, an expression for density or specific heat capacity involving the CEL variable `p` will still use relative pressure.

The ranges are required to enable the CFX-Solver to construct a property table for the pressure-temperature-enthalpy relationship as well as entropy and, when using the Redlich Kwong and IAPWS equations of state, density and specific heat capacity.

Additional information on fluid properties and the treatment of enthalpy in ANSYS CFX is available in Equations of State in the CFX-Solver Theory Guide.

Release 18.2 - © ANSYS, Inc. All rights reserved.