15.4 Species Transport Without Reactions

In addition to the volumetric and surface reactions described in the previous sections, you can also use ANSYS FLUENT to solve a species mixing problem without reactions. The species transport equations that ANSYS FLUENT will solve are described in this section in the separate Theory Guide , and the procedure you will follow to set up the non-reacting species transport problem is the same as that described in Sections  15.1.1- 15.1.6, with some simplifications.

The basic steps are listed below:

1.   Enable Species Transport in the Species Model dialog box and select the appropriate Mixture Material.

Models Species Edit...

See Section  15.1.1 for information about the mixture material concept, and Section  15.1.2 for more details about using the Species Model dialog box.

2.   (optional) If you want to model full multicomponent (Stefan-Maxwell) diffusion or thermal (Soret) diffusion, enable the Full Multicomponent Diffusion or Thermal Diffusion option.

3.   Check and/or define the properties of the mixture and its constituent species.

Materials

Mixture properties include the following:

• species in the mixture

• other physical properties (e.g., viscosity, specific heat)

See Section  15.1.3 for details.

4.   Set species boundary conditions, as described in Section  15.1.5.

No special solution procedures are usually required for a non-reacting species transport calculation. Upon completion of the calculation, you can display or report the following quantities:

• Mass fraction of species-n

• Mole fraction of species-n

• Concentration of species-n

• Lam Diff Coef of species-n

• Eff Diff Coef of species-n

• Enthalpy of species-n (pressure-based solver calculations only)

• Relative Humidity

• Mean Molecular Weight

• Liquid species mass fraction of species-n (solidification and melting model only)

These variables are contained in the Species... and Properties... categories of the variable selection drop-down list that appears in postprocessing dialog boxes. See Chapter  31 for a complete list of flow variables, field functions, and their definitions. Chapters  29 and 30 explain how to generate graphics displays and reports of data.