Defining the Multispecies Conditions at a Wall

You can define the relative concentration of each species next to a wall in a multispecies flow simulation.

For each definition method, you can define species concentration values that are uniform throughout space, or you can define values that vary in space according to a mapped spatial field.

See Also
Defining a Wall
  1. From the Wall dialog box, expand the Multispecies Conditions options.
  2. Define the behavior of each species at the wall boundary:
    OptionDescription
    Zero Flux Species behavior does not change at the wall boundary.
    Fully Catalytic Species concentration changes at the wall.
    Constant Mass Flux Species has a constant flux at the wall.
    Absorption or Production Species are partially absorbed or produced by the wall.
  3. For species that exhibit fully catalytic behavior at the wall, enter a value for the Mass fraction of the species at the wall.
  4. For species that exhibit constant mass flux at the wall, enter a value for the Mass flux of the species at the wall.
  5. For species that are partially absorbed or produced by the wall, enter a value for the Absorption or production rate and Reference mass fraction.

    The app calculates absorption using the equation q = β ( C − C 0 ) , where q is the absorption coefficient, C 0 is the reference mass fraction, and C is the local mass fraction near the wall.

  6. Optional: For an active multispecies simulation, include water evaporation and condensation effects at the wall by doing the following:
    1. Expand the Tag material section.
    2. Select Include fluid film phase change.
    3. Specify the Initial film thickness of water at the wall boundary.