Defining a Pressure Outlet

You can define the fluid pressure at the opening where the flow leaves the fluid domain.

Note: The outlets you specify for your simulation must all be of the same type. You cannot create a simulation that uses both mass flow split outlets and pressure outlets.

See Also
About Outlets
Defining the Fluid Physics of a Flow Simulation
In Other Guides
Editing Simulation Features
Defining a Fluid Domain
  1. From the Flow section of the action bar, click Pressure Outlet .
  2. Optional: Enter a descriptive Name.
  3. Select the surface where fluid leaves the domain.
  4. Specify the Static pressure at the opening where the fluid leaves the fluid domain.

    You can use a single uniform value, spatially-varying mapped data, or a JavaScript user subroutines that defines the value programmatically.

    In addition, you can apply a scale factor or amplitude to the value. Click , then specify either or both of the following:

    OptionDescription
    Scale factor A multiplier that the app applies to the magnitude of the value in the step.
    Amplitude Name of the amplitude curve that defines the magnitude of the value during the step.
  5. Optional: Expand the Recirculation conditions options and specify the Temperature of the fluid flowing back into this pressure outlet from the environment.

    You can use a single uniform value, spatially-varying mapped data, or a JavaScript user subroutines that defines the value programmatically.

    In addition, you can apply a scale factor or amplitude to the value. Click , then specify either or both of the following:

    OptionDescription
    Scale factor A multiplier that the app applies to the magnitude of the value in the step.
    Amplitude Name of the amplitude curve that defines the magnitude of the value during the step.
  6. Optional: If a turbulence model is specified in the physics of the simulation, you can select a Turbulence specification and choose turbulence parameters for the pressure outlet.

    The specific turbulence customization settings that appear depend on your specification choice and on the turbulence model you chose in the physics definition. For a full description of all available turbulence settings, see Initial Turbulence Options.

  7. Optional: For multispecies flow analyses, you can also specify the mass fraction for the secondary species at the pressure outlet. Specify the mass fractions of the nonbackground species as a decimal value, such as 0.15. After you specify these nonbackground species, the app assigns the remainder as the mass fraction of the background species.
  8. For multiphase flow analyses with the volume of fluid (VOF) method, you can specify the recirculating material distribution. Specify a fluid fraction value of 1 for the reference material or a value of 0 for the secondary material.

    You can also specify a spatially varying material distribution by selecting Mapped spatial data from the distribution options. This option is equivalent to how a spatially varying initial fluid fraction is defined; see Defining Initial Fluid Fractions for a VOF Method Analysis for details. For example, assume you are performing a wave simulation with wave damping enabled at pressure outlets to keep the free-surface elevation at a constant level. In this case, you would need to specify, as recirculating material, the reference material below the free-surface elevation and the secondary material above that level.

  9. If surface-to-surface radiation is enabled in the fluid physics, specify one of the following from the Opening radiation condition options:
    Wall typeDescription
    On: Use radiation temp Specifies a radiation temperature to be used in the radiative heat flux calculation at this opening. It is useful when the external temperature that dominants the radiation effects is different from the flow temperature. You can also adjust the emissivity between zero and one. Both the radiation temperature and emissivity can be specified using an uniform value or spatially-varying mapped data.
    On: Use flow temp Uses the flow temperature in the radiative heat flux calculation at this opening. You can specify a uniform value or spatially-varying mapped data for the emissivity. The emissivity has to be between zero and one.
    Off The boundary does not participate in the view factor computation; that is, the boundary is transparent to radiation.
  10. Click OK.