Comments

• DaveStupple

  January 23 edited January 23

  Line 1 should read 'except a few wedges away from the heat load' and line 8, '5 to 7'.
• JohnM

  January 23

  The pyramids are occasionally cursed. I have had problems with this using the local refine, mostly on structural stuff. With this being a thermal and only 1DOF/node, can you get away with refining the whole model?
• DaveStupple

  January 23

  Thanks JohnM, appreciated. I could certainly give it a go. It will be ungainly. First I'll try all hex and tied contacts. I'm nearly in a position to run this.
• Victor

  January 24

  Since you've already scaled it up enough to avoid the negative Jacobian error, I don't think there's any value in scaling it up beyond that. It might push something over the limit in the other direction.
  
  Pyramids are mostly bad for boundary conditions and accuracy but you could delete them to see if it fixes it.
  
  You can change to linear elements for faster iterations in debugging it.
  
  You can also try deleting big chunks of the model until it works. You can usually pretty quickly zero in on what's causing the problem that way.
  
  
• DaveStupple

  January 30 edited January 30

  Eagle-eyed Victor spotted a typo in which an internal heat constraint had a value of
  
  7.272727+15
  
  when it should have been
  
  7.272727E+15
  
  What our production manager would call a code 18 fault, because the source of the problem is about 18 inches from the monitor.
  
  So my conformal mesh 1000x scale model solves OK with the typo corrected. I tried to run the other model that was pretty much ready to go, with a finer mesh connected to the coarser mesh by bonded tied contact. I get loads of these messages:
  
  *WARNING in gentiedmpc:
  DOF 0 of node 636371 is not active;
  no tied constraint is generated
  
  As far as I can see, the contact constraints look ok, but I must be missing something.
  
  Edit: would the problem be that nodes on edges appear in two separate contact constraints?
• Victor

  January 31 edited January 31

  I'm not sure what those warnings mean. I didn't know there was a DOF 0 in CCX. Normally there are similar but different warnings for nodes that aren't connected by the contact, such as if one surface extends beyond the edge of the other, which is harmless. But they might also be too far apart and not connected at all. See if the deformed view shows them deforming together all over, of it some parts appear disconnected.
  
  It is possible that it's because of nodes are shared by two contacts. If that's the problem, use elastic contact instead, which doesn't have complications from MPC conflicts.
• DaveStupple

  February 2

  Thanks Victor, It's a thermal static, so is there even a deformed view? I checked all the rows and columns of nodes, all share the correct x, y, z coordinate as appropriate. I'll try elastic. This is not a big thing as I have a conformal mesh mesh model solving fine, but as I had a contact model nearly ready to go, I thought it might be interesting for the group to see the comparison. Thanks for reading and replying.