Learning Forum

[Juan Martín Morrone]

Hello everyone!

I am simulating a brake disc in CFX, but I have a problem with the air mesh surrounding the rotor. With a first rotor model I had no problem and I was able to apply sweep method achieving a good mesh quality (first two pictures).
When I want to apply the sweep method at the second rotor model (which has a little geometry difference), the next error message appears:
"The meshing failed due to quality checks. The mesh does not meet the specified Shape Checking constraints specified. Please look at the mesh quality and adjust meshing options or mesh sizes to obtain a better quality mesh, or relax the shape checks."
I have tried to improve the mesh quality but I couldn't. I really want to fix this problem because, otherwise, I should apply a tetrahedrons method which is less effective.
I would really apreciate your help, since this proyect is realy important to me.

Notes: The rotor mesh is not showed.
             I have made sure that the air domain of the second model is sweepable with the "Show Sweepable Bodies" tool.

 

[Rob]

I don't think the lower volume can be swept. Can you project the "source" face of the sweep to the "target" and does the cross section change significantly? 

[Juan Martín Morrone]

Thanks for answering. As I mentioned before, according to the "Show Sweepable Bodies" tool, the domain is sweepable. However, I don't know if the tool is always reliable.
I have attached a picture which shows the change of the cross section more clearly. I hope you can say me if exist a way to apply the sweep method or if I should change to another method.

Regards.

[Rob]

It's technically sweepable as the volume passes the checks. However the highlighted section will cause problems, and most likely explains the failure. Have a look at mesh decomposition and selective meshing: I'd mesh most of that with hex and only a fairly small section with tets.

Actually I'd poly mesh the lot but I don't have to worry too much about compute resource and I'm lazy.... 

[Juan Martín Morrone]

Thank you so much rwoolhou, I'm going to follow your advice of mesh decomposition. I will tell you the results.

Regards.

[Juan Martín Morrone]

Well, I have divided the body in two. The part with the section highlighted in the previous photo was meshed with tets, while the rest was meshed with hex. I was able to get a good mesh quality and had no problems with fluid-solid interfaces.
Thanks for your help rwoolhou!

Regards