TUREK HRON case -Problem of negative error in this case

- August 16, 2023 at 4:38 am
  
  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.
- August 16, 2023 at 2:37 pm
  
  Federico
  Ansys Employee
  
  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.
  - August 17, 2023 at 10:35 am
    
    SHAHIM HAIDER ABIDI
    Subscriber
    
    tetra elements only, with smoothing and remeshing with time step .005 seconds
    - August 17, 2023 at 2:53 pm
      
      Federico
      Ansys Employee
      
      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.
    - August 18, 2023 at 4:22 am
      
      SHAHIM HAIDER ABIDI
      Subscriber
      
      yes element size is .005 and velocity is 1.5m/s. time step is .001
    - August 18, 2023 at 3:41 pm
      
      Federico
      Ansys Employee
      
      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?
- August 31, 2023 at 10:07 am
  
  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
  - August 31, 2023 at 1:15 pm
    
    Federico
    Ansys Employee
    
    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)