Fluids

Fluids

Pressure outlet Boundary conditions

    • Abbas2020
      Subscriber

      Hi everyone,

      In the pressure outlet dialog box, I would like to know what type of boundary condition is applied to the energy equation. Regardless of the backflow temperature which is used in the case if there is a backflow that occurs in the outlet section.

      As far as I know, there is another boundary condition for outlet available in Fluent called " Outflow condition" in which it is assumed a zero-gradient condition for all variables including temperature.

      Can anyone tell if this zero-gradient is applied also for temperature within the " pressure outlet condition"?

    • Rob
      Ansys Employee
      If you have reverse flow the pressure boundary will add material at the temperature you specify. The old outflow boundary shouldn't be used, and I've not used it since Fluent 4.
    • Abbas2020
      Subscriber
      I don't understand, how the pressure boundary will add material?
    • Abbas2020
      Subscriber
      This temperature specified in the pressure boundary is for backflow occurring in the outlet section. In case, there is no backflow, what will be taken as a boundary in the outlet section for the energy equation?
    • Rob
      Ansys Employee
      If there's no backflow the boundary temperature won't do anything. By add material I mean flow enters through the outlet in the reverse flow condition: material is added to the domain.
    • Abbas2020
      Subscriber
      OK.
      But in the case of conjugate heat transfer simulation between two fluids and a solid wall, does the energy equation need to include a temperature boundary for the diffusion term in the outlet? or thefluent with pressure-outlet boundary conditions also considers a zero-gradient temperature?.
    • DrAmine
      Ansys Employee
      If no backflow occurs we assume high Peclet Number and hence temperature gradient is zero at outlet.
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