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new geometrie in the moving mesh appl. mode
Posted Jun 17, 2009, 4:51 a.m. EDT 4 Replies
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I calculate a transient moving mesh in a axi-symmetrical model. By aid of postprocessing -> subdomain integration I evaluate the volume of my geometry:
t=0 I get V1
t=t_stop I get V2
After creating a new geometry from the deformed mesh I check the volume:
for t=0 I get V3 and V3 > V2 !!
I expected V3=V2!
Is there anybody who gets the same results and who knows the reason to prevent this difference?
********** Note! *****************
The volume "increases" by updating the model after creating the new geometry from the deformed mesh.
*********************************
Thank you and best regards
Michael
t=0 I get V1
t=t_stop I get V2
After creating a new geometry from the deformed mesh I check the volume:
for t=0 I get V3 and V3 > V2 !!
I expected V3=V2!
Is there anybody who gets the same results and who knows the reason to prevent this difference?
********** Note! *****************
The volume "increases" by updating the model after creating the new geometry from the deformed mesh.
*********************************
Thank you and best regards
Michael
4 Replies Last Post Jun 26, 2009, 11:06 a.m. EDT
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Posted:
2 decades ago
Hi Michael,
How large are the differences you see? If there are pretty small, it is possible that this is just a post-processing/meshing issue? (the volume is calculated based on whatever mesh you have before and after remeshing -- a finer mesh that would represent the geometry a bit different could give a slightly different answer)?
Mina Sierou, COMSOL Inc
How large are the differences you see? If there are pretty small, it is possible that this is just a post-processing/meshing issue? (the volume is calculated based on whatever mesh you have before and after remeshing -- a finer mesh that would represent the geometry a bit different could give a slightly different answer)?
Mina Sierou, COMSOL Inc
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Posted:
2 decades ago
Dear Mina,
the differences are very high, about 30-40%! The reason is - I tested it using a small model - that I start a new time stepping after recreating the new geometry and remeshing.
- evaluate V0(t=0) (step 1)
- simulating ALE t=0,....,1
- evaluate V1(t=1) (step 1)
- creating new geometry
- remeshing
- evaluate V1(t=1) (step 2) it agrees with V1 from step 1
- evaluate V0(t=0) (step 2) it doesn't agree with V0 from step 1 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Because I don't restart the model but I start a new solver sequence after remeshing and new time stepping, the volumes differ. But there must be a way to prevent this case!
Best regards
Michael
the differences are very high, about 30-40%! The reason is - I tested it using a small model - that I start a new time stepping after recreating the new geometry and remeshing.
- evaluate V0(t=0) (step 1)
- simulating ALE t=0,....,1
- evaluate V1(t=1) (step 1)
- creating new geometry
- remeshing
- evaluate V1(t=1) (step 2) it agrees with V1 from step 1
- evaluate V0(t=0) (step 2) it doesn't agree with V0 from step 1 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Because I don't restart the model but I start a new solver sequence after remeshing and new time stepping, the volumes differ. But there must be a way to prevent this case!
Best regards
Michael
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Posted:
2 decades ago
Hi, there is probably some conceptual mistake in the model. If you submit the model to this thread or support@comsol.com I am sure the problem will be resolved by somebody.
Niklas
Niklas
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Posted:
2 decades ago
Hello Niklas,
the case is supported by Ms. Bannach and Mr. Geis from Comsol Germany (Göttingen). There are some activities in the "background", thats why I dont send the model file again. Hope the reasons will be found next week.
Today we set up mass transport for the k-eps turbulence model. It should be included in the next version of comsol! Now the model of a large cavern runs perfectly.
Best regards
Michael Rembe
the case is supported by Ms. Bannach and Mr. Geis from Comsol Germany (Göttingen). There are some activities in the "background", thats why I dont send the model file again. Hope the reasons will be found next week.
Today we set up mass transport for the k-eps turbulence model. It should be included in the next version of comsol! Now the model of a large cavern runs perfectly.
Best regards
Michael Rembe