When you use one of the general multiphase models, some additional field functions will be available for postprocessing, as listed in this section. Most field functions that are available in single phase calculations will be available for either the mixture or each individual phase, as appropriate for the general multiphase model and specific options that you are using. See Field Function Definitions for a complete list of field functions and their definitions. Displaying Graphics and Reporting Alphanumeric Data explain how to generate graphics displays and reports of data.

 

26.10.1.4. Multiphase Species Transport

For calculations using species transport with either of the multiphase models, you can generate graphical plots or alphanumeric reports of the following additional items:

• Mass Fraction of species-n (in the Species... category)

  This item is available for each species.

• Mole Fraction of species-n (in the Species... category)

  This item is available for each species.

• Molar Concentration of species-n (in the Species... category)

  This item is available for each species.

• Lam. Diff Coeff of species-n (in the Species... category)

  This item is available for each species.

• Eff. Diff. Coeff. of species-n (in the Species... category)

  This item is available for each species.

• Enthalpy of species-n (in the Species... category)

  This item is available for each species.

• Relative Humidity (in the Species... category).

• Turbulent Rate of Reaction-n (in the Reactions... category)

  This item is available for each species.

• Rate of Reaction (in the Reactions... category).

• Mass Transfer Rate n (in the Phase Interaction... category)

  This item is available for each mass transfer mechanism that you defined.

• Saturation Vapor Pressure n (in the Phase Interaction... category)

  This item is available for each cavitation mass transfer mechanism that you defined.

• Mass Concentration of species-n (Phase Level) (in the Species... category)

  This item is available for all the phases that have species components.

• Mass Concentration of species-n (Mixture Level) (in the Species... category)

  This item is available for all the phases that have species components.

Thermal quantities will be available only for calculations that include the energy equation.

Computing Mass of a Component in a Phase

The volume integral is always calculated at the mixture level for the whole cell volume. Therefore, you can use a Volume Integral of Mass Concentration of species-n (Mixture Level) to compute the mass of a phase component . The reported value will be calculated as:

where

= density of phase

= mass fraction of component in phase

= mass fraction of component in phase

= volume fraction of phase

= cell volume

For mixture and Eulerian calculations, it is possible to display velocity vectors for the individual phases using the Vectors dialog box.

 Results → Graphics → Vectors  Edit...

To display the velocity of a particular phase, select Velocity in the Vectors of drop-down list, and then select the desired phase in the Phase drop-down list. You can also choose Relative Velocity to display the phase velocity relative to a moving reference frame. To display the mixture velocity (relevant for mixture model calculations only), select Velocity (or Relative Velocity for the mixture velocity relative to a moving reference frame), and mixture as the Phase. Note that you can color vectors by values of any available variable, for any phase you defined. To do so, make the appropriate selections in the Color by and following Phase drop-down lists.

When you use the Flux Reports dialog box to compute fluxes through boundaries, you will be able to specify whether the report is for the mixture or for an individual phase.

 Results → Reports → Fluxes Edit...

Select mixture in the Phase drop-down list at the bottom of the dialog box to report fluxes for the mixture, or select the name of a phase to report fluxes just for that phase.

When mass transfer is included in multiphase simulations, Ansys Fluent by default uses the following sensible enthalpy definition for the reporting of the enthalpies and total heat transfer rate:

where is the phase temperature for the Eulerian multiphase model or the mixture temperature for all other multiphase models, is the reference temperature, is the formation enthalpy at , and is the specific heat. The values for , , and are those you specified in the Create/Edit Materials dialog box.

The mixture enthalpy is calculated as a mass-weighted average of the phase enthalpies.

For Eulerian calculations, when you use the Force Reports dialog box to compute forces or moments on wall boundaries, you will be able to specify the individual phase for which you want to compute the forces.

 Results → Reports → Forces Edit...

Select the name of the desired phase in the Phase drop-down list on the left side of the dialog box.

You can obtain a report of mass flow rate for each phase (and the mixture) through each flow boundary using the report/fluxes/mass-flow text command:

report → fluxes → mass-flow

When you specify the phase of interest (the mixture or an individual phase), Ansys Fluent will give you the option to list each zone, followed by a summary of the mass flow rate through that zone for the specified phase, or will summarize the mass flow rate for all zones. An example is shown below, demonstrating how to list the mass flow rate for all zones.

/report/fluxes> mf
(mixture water air)
domain id/name [mixture] air
all boundary/interior zones [yes]
Write to File? [no]

                             air
                  Mass Flow Rate               (kg/s)
-------------------------------- --------------------
             spiral-press-outlet           -1.2330244
                 pressure-outlet           -9.7560663
                spiral-vel-inlet            0.6150589
                           walls                    0
                  velocity-inlet            4.9132133
                ---------------- --------------------
                              Net           -5.4608185