Fluent meshing – bounding box not matching

- July 1, 2022 at 8:46 am
  
  s.petley
  Subscriber
  
  When I create my geometry in DesignModeller I can check that the centroid is 0,0, however when I import to Fluent meshing the bounding box is no longer symmetrical. While the numbers are very small since this is a simulation with rotating sections I think this is what is causing the stability problems I am having further down the line. Is there a way to overcome this problem?
- July 1, 2022 at 10:26 am
  
  Rob
  Ansys Employee
  
  That shouldn't cause any problems, and tends to be meshing tolerance related. What are you modelling?
  - July 1, 2022 at 11:05 am
    
    s.petley
    Subscriber
    
    I'm having trouble submitting my reply. I click submit then it looses the post
  - July 1, 2022 at 11:07 am
    
    s.petley
    Subscriber
    
    Ok, seems to be working now. I'm modelling a rotary hydrocyclone. Currently I'm looking at tangential inlet slots vs vanes to give the swirl component pre-rotating section. The simulation with the slots does not have this geometry issue and was very stable and converged well, the one with the vanes was not. I've attached two tangential velocity plots and the area of concern is at the far end by the cone, which I thought could be geometry related as they were meshed identically. Also, I noticed when I go to create the plane the centre is not at 0,0...also attached. Perhaps I should put these as my frame motion coordinates?
  - July 1, 2022 at 11:07 am
    
    s.petley
    Subscriber
  - July 1, 2022 at 11:08 am
    
    s.petley
    Subscriber
  - July 1, 2022 at 11:08 am
    
    s.petley
    Subscriber
- July 1, 2022 at 12:26 pm
  
  Rob
  Ansys Employee
  
  Check the mesh around the vanes. A slight offset on the centreline won't effect a single domain system, and won't do much to upset a sliding mesh system either. Chances are there's a flow separation or squashed cell on the vanes.
  - July 1, 2022 at 3:35 pm
    
    s.petley
    Subscriber
    
    Ok thanks, I will investigate the mesh a little more.

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