Fluids

Fluids

Fluent Simulation Does Not Re-Mesh

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    • ahg
      Subscriber

      Hello,

      I am trying to run a simulation where a 'rocket' (triangular section) moves laterally within an enclosure due to the surrounding fluid flow pushing it forward.

    • Rob
      Ansys Employee
      Have a look in the Help system for Fluent. There are two videos that go through moving mesh. In your case I think you've tried to smooth the mesh rather than remesh. n
    • ahg
      Subscriber
      Hi Rob,nThanks for your advice. Regarding the smoothing, I think that i just a poor screenshot on my part, the re-meshing option (deselecting the smoothing made no difference):nI haven't been able to find the videos you are referring to, seems like the help only includes descriptions, but I will investigate further and see whether they help. I've tried to follow videos off YouTube, but I can't spot the error.nThanks again for your help,nAtreyn
    • Rob
      Ansys Employee
      Check the cell size in your model compared to the remesh criterion too: the defaults aren't always appropriate. n
    • ahg
      Subscriber
      Hi Rob,nThanks again.nI believe the cell size in the model matches the remesh criteria (~max cell size 5.8e-4). A maximum cell skewness is also set of 0.7, which I think should trigger the remeshing, before negative cells occur.nBest,nAtreyn
    • Rob
      Ansys Employee
      I should have spotted this, check 11.6.2.3 in the Fluent User's Guide, Solution mode, 2020R2 documentation. n
    • ahg
      Subscriber
      Hi Rob,nJust to clarify, are you saying that using a triangular mesh will resolve this? I have tried this with the local cell remeshing and a triangular mesh, and am now receive a floating point error.nI am still messing around with the settings to hopefully try resolve this as it does appear to be a different problem.nThanks a bunch.nAtreynnEDIT: It appears the floating point error occured because I had switched to a pressure based solver. If I was to switch back to a density solver the divergence occurs, and negative cell volume occurs again.n
    • Rob
      Ansys Employee
      Is the solution remeshing, and then failing?n
    • ahg
      Subscriber
      Hi Rob,nThe solution looks to just be failing. No remeshing appears to be taking place - is there any way to check in the logs or similar?nThanks,nAtreyn
    • Rob
      Ansys Employee
      Logs tend to tell you what happened, what you want is images at each mesh update. If you display cell size how does that compare to the remesh settings? n
    • ahg
      Subscriber
      Hi Rob,nThanks for your advice. I was unable to get this dynamic mesh to work, so have opted for a different approach. As such, am happy to close this thread. nThanks,nAtreyn
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