Elements Concentrations Caused by Tetra Remesh

Altair Forum User

Hi,

 

I have been frequently using the the tetra remeshing function to remesh the deformed meshes created by FE analysis in order to carry out subsequent analyses. However, some parts of the mesh gets finer and finer after every time being remeshed (as shown in the pic). These element concentrations are undesired and they largely increases computation cost. Also, the degree of concentration increases rapidly with the number of remesh process being applied which eventually cause difficulties in carrying out efficient FE analysis.

 

I wonder if there is any function available to coarsen these small elements? I can accept the lost in boundary geometry accuracy.   I have tried limiting the min element size for remeshing, this problem is mitigated but can't be completely solved - extremely small elements still occur after a large amount of remesh processes. I suspect these concentration in elements are created by HM in order to exactly track the deformed mesh - but I can't find any 'feature angle' parameters that can be adjusted to ignore certain geometry features of the deformed meshes. Any alternative solutions?

 

picture: https://drive.google.com/file/d/0B8pqXnKPKIghWlpMY21MYllKWkk/view?usp=sharing

 

Many thanks,

Wensong

 

P.S. Here is another picture showing the remesh result after roughly 20 FE analysis steps with HM remeshing in between of each step.

https://drive.google.com/file/d/0B8pqXnKPKIghb2hfVkduNWZVWkk/view?usp=sharing

Altair Forum User

Hi,

I have already seen sometime this problem. I think that due to geometrical issues.

If that is not desired for you, try to modify locally this area by cutting your surfaces by a cicle for example (see picture).

Maybe you need manually modify some elements.

 

But I don't know how to fix that during a 'batch' remesh process.

 

Altair Forum User

Altair Forum User said:

Hi,

I have already seen sometime this problem. I think that due to geometrical issues.

If that is not desired for you, try to modify locally this area by cutting your surfaces by a cicle for example (see picture).

Maybe you need manually modify some elements.

 

But I don't know how to fix that during a 'batch' remesh process.

 

Hi Nguyen-Dai,

 

Thanks for your reply. Yes, I agree with you that it is most probably due to geometrical issues - sharper corners etc. However, what do you mean by 'cutting your surfaces by a circle for example'? I can't see any picture attached with your post. Also, since it is a mesh part being imported into HM every time, I am afraid I don't have any geometry entities with the model. Is it possible to coarsen the mesh somehow?

 

Thanks a lot.

Wensong

Altair Forum User

Sorry, I can't attach my picture becasue of forum's bug.

If you don't have geometry, try to remove all 'small' elements within this area, build a approximate surface and make the mesh again. In this case, maybe I have to do equivalent of nodes to your old mesh.