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TUREK HRON case -Problem of negative error in this case

    • SHAHIM HAIDER ABIDI
      Subscriber

      what settings of smoothing and remeshing we should take for turek hron case , so that we can avoid negative volume error.

    • Federico Alzamora Previtali
      Subscriber

      Hello, 

      What types of cells are you using in your mesh? Can you show a screenshot of your setup?

      The default remeshing/smoothing methods should work fine for this case: unified remeshing with spring smoothing. Negative volume error can also occur if your time step is too large for the resulting displacement.

      • SHAHIM HAIDER ABIDI
        Subscriber

        tetra elements only, with smoothing and remeshing with time step .005 seconds

        • Federico Alzamora Previtali
          Subscriber

          How does this time step compare with the size of your elements near the moving boundary? Remember time step delta t <= mesh size/boundary velocity.

        • SHAHIM HAIDER ABIDI
          Subscriber

          yes element size is .005 and velocity is 1.5m/s. time step is .001

        • Federico Alzamora Previtali
          Subscriber

          Time step of 0.001s should be fine then, but 0.005s which you mentioned earlier would be too large. If the problem persists, please provide more details:

          What are your remeshing settings?

          How are your Dynamic Mesh zones set?

    • SHAHIM HAIDER ABIDI
      Subscriber

      even with that also, I am not getting.

      Remeshing- local cell , size interval 1, 0.7.

      In dynamic zone interface , i had taken as system coupling and symmetry as deforming

      • Federico Alzamora Previtali
        Subscriber

        Hello, 

        It is really difficult for me to provide specific recommendations if I don't have any visuals of your model or any reference to the zones that you mention.

        You can read on the various Dynamic Mesh settings in the Fluent User Guide: 12.6. Using Dynamic Meshes (ansys.com)

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