24.3.6 Modeling Compressible Flows

If you are using the VOF model for a compressible flow, note the following:

• Only one of the phases can be defined as a compressible ideal gas (i.e., you can select the ideal gas law for the density of only one phase's material). There is no limitation on using compressible liquids using user-defined functions.

• When using the VOF model, for stability reasons, it is better (although not required) if the primary phase is a compressible ideal gas.

• If you specify the total pressure at a boundary (e.g., for a pressure inlet or intake fan) the specified value for temperature at that boundary will be used as total temperature for the compressible phase, and as static temperature for the other phases (which are incompressible).

• For each mass flow inlet, you will need to specify mass flow or mass flux for each individual phase.

  Note that if you read a case file that was set up in a version of ANSYS FLUENT previous to 6.1, you will need to redefine the conditions at the mass flow inlets. See Section  24.2.9 for more information on defining conditions for a mass flow inlet in VOF multiphase calculations.

See Section  9.4 for more information about compressible flows.