24.8.1 Model-Specific Variables

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 Chapter  31 for a complete list of field functions and their definitions. Chapters  29 and 30 explain how to generate graphics displays and reports of data.

VOF Model

For VOF calculations you can generate graphical plots or alphanumeric reports of the following additional item:

• Volume fraction (in the Phases... category)

  This item is available for each phase.

The variables that are not phase specific are available (e.g., variables in the Pressure... and Velocity... categories) represent mixture quantities. Thermal quantities will be available only for calculations that include the energy equation.

Mixture Model

For calculations with the mixture model, you can generate graphical plots or alphanumeric reports of the following additional items:

• Diameter (in the Properties... category)

  This item is available only for secondary phases.

• Volume fraction (in the Phases... category)

  This item is available only for secondary phases.

• Interfacial Area Concentration (in the Interfacial Area Concentration... category)

  This item is available only for secondary phases.

The variables that are not phase specific are available (e.g., variables in the Pressure... category) represent mixture quantities. Thermal quantities will be available only for calculations that include the energy equation.

Eulerian Model

For Eulerian multiphase calculations you can generate graphical plots or alphanumeric reports of the following additional items:

• Diameter (in the Properties... category)

  This item is available only for secondary phases.

• Granular Conductivity (in the Properties... category)

  This item is available only for granular phases.

• Granular Pressure (in the Granular Pressure... category)

  This item is available only for granular phases.

• Granular Temperature (in the Granular Temperature... category)

  This item is available only for granular phases.

• Volume fraction (in the Phases... category)

  This item is available only for secondary phases.

• Interfacial Area Concentration (in the Interfacial Area Concentration... category)

  This item is available only for secondary phases.

The availability of turbulence quantities will depend on which multiphase turbulence model you used in the calculation. Thermal quantities will be available (on a per-phase basis) only for calculations that include the energy equation.

More advanced options for the mixture phase are available under the Phases... category, allowing you to select from a list of variables to postprocess. To access the entire list in the GUI, type the following text command:

solve $\rightarrow$ set $\rightarrow$ expert

Retain most of the default setttings, except when asked to Keep temporary solver memory from being freed?. Answering yes to this question will expose a list under the Phases category for the mixture phase, one of which will be the Phase ID. Selecting this option allows you to plot contours of phase IDs for the volume fraction, which will facilitate phase distribution display when more than two phases are present for free surface calculations.

This option is available for all the multiphase models. However, note that only cell values should be plotted for this option. Make sure that the Node Values option is not selected as it will show the wrong phase ID contours at the interface.

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.

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

Wet Steam Model

ANSYS FLUENT provides a wide range of postprocessing information related to the wet steam model.

The wet steam related items can be found in Wet Steam.... category of the variable selection drop-down list that appears in the postprocessing dialog boxes.

• Liquid Mass Fraction

• Liquid Mass Generation Rate

• Log10(Droplets Per Unit Volume)

• Log10(Droplets Nucleation Rate)

• Steam Density (Gas-Phase)

• Liquid Density (Liquid-Phase)

• Mixture Density

• Saturation Ratio

• Saturation Pressure

• Saturation Temperature

• Subcooled Vapor Temperature

• Droplet Surface Tension

• Droplet Critical Radius (microns)

• Droplet Average Radius (microns)

• Droplet Growth Rate (microns/s)

Dense Discrete Phase Model

For postprocessing, both the DPM and the Eulerian multiphase capabilities are retained. In addition to usual DPM postprocessing (Section  23.7), you can display, for example, vector plots of the particle's velocity field. Make sure to select the discrete phase from the Phase drop-down list. For transient simulations which include the dense discrete phase model, you can display the following when the Unsteady Statistics... category is selected:

• Mean Velocity

• Mean Volume Fraction

• Mean Phase Diameter

• RMS Velocity

• RMS Volume Fraction

• RMS Phase Diameter

For the Unsteady Statistics... category to appear in the postprocessing dialog boxes, make sure that Data Sampling for Time Statistics is enabled in the Run Calculation task page, and that you have performed the calculation.