Fluids

Fluids

Porous jump calculation behaviour

    • Dipankar Baruah
      Subscriber

      Hello, I am encountering a situation in my fluent flow simulation where I am using a interface as Porous jump. Due to complexity of the model, there is revese flow through the porous jump. While the simulation runs, it shows a notification "Reverse porous jump zone 156 orientation based on bulk flow direction....done". Now my question is , the reverse flow is happening only in some region of the porous jump (>50% of area) but not all the region. will the reversing of the porous jump orientation effect the pressure vs velocity calculations in the region where the reverse flow is not happening. i hope my question is clear. if not let me know.

    • Rob
      Ansys Employee

      Hopefully that's an interior and not an interface: there's a difference in Fluent but I also appreciate the words don't always translate well. Look in the Boundary Condition section of the manual to see the difference. 

      Reverse flow shouldn't cause any problems: if you plot pressure how does it look? 

    • Dipankar Baruah
      Subscriber

      Hello,

      The pressure plot shows that there is a pressure build up above the porous jump surface, which should be the actual case. So pressure drop looks fine, but there is a sudden spike in the residuals whenver there is a change in orientation of the porous jump surface. Any idea why is that happening ?

    • Rob
      Ansys Employee

      Some images may help. Have you got an unstable flow feature. 

    • Dipankar Baruah
      Subscriber

      What are you refereing to by unstable flow feature ? The geometry is not a simple pipe, but its pretty complex leading to recirculations in the domain.

    • Rob
      Ansys Employee

      A flow feature that's not stable. Like a complex recirculation or attachment/detachment position. The steady solver may have identified multiple "stable" solutions so may be drifting between them. Hence wanting images, a residual plot will also be useful. 

    • Dipankar Baruah
      Subscriber

      Give me one day to get you the images of the residuals.

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