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v4.0a - identity and contact pairs
Posted Nov 19, 2010, 4:39 p.m. EST 3 Replies
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When should I define identity and contact pairs in my geometry?
An example for each case would be very helpful.
If I have a geometry that consists of a fluid domain (which is blood) and an artery and the blood flows inside the artery, then do I need to define a contact pair in addition to using the FSI?
Also the users manual says that the contact and identity pairs can be used only for assemblies. However when using COMSOL 4.0 and higher isn't it mandatory to form an union before running an analysis? I remember reading this somewhere but now I am totally confused and am wondering if I misunderstood the statement about mandatory union formation.
Thanks for the help.
Sirisha
An example for each case would be very helpful.
If I have a geometry that consists of a fluid domain (which is blood) and an artery and the blood flows inside the artery, then do I need to define a contact pair in addition to using the FSI?
Also the users manual says that the contact and identity pairs can be used only for assemblies. However when using COMSOL 4.0 and higher isn't it mandatory to form an union before running an analysis? I remember reading this somewhere but now I am totally confused and am wondering if I misunderstood the statement about mandatory union formation.
Thanks for the help.
Sirisha
3 Replies Last Post Nov 21, 2010, 4:16 a.m. EST
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Posted:
1 decade ago
Hi
Contact pairs are for object that might interact intermittently, that might not be in contact all the time, in FSI you mostly have the liquide always in contact with the structure (except for waves perhaps) even if the liquid flows.
Contact requires assembly mode to dissociate the boundaries for the domains in contact (but not for the others so if you have many domains, group them in a composite object to have automatically continuity for these boundaries and leave the assembly mode for the interactions between composite objects
--
Good luck
Ivar
Contact pairs are for object that might interact intermittently, that might not be in contact all the time, in FSI you mostly have the liquide always in contact with the structure (except for waves perhaps) even if the liquid flows.
Contact requires assembly mode to dissociate the boundaries for the domains in contact (but not for the others so if you have many domains, group them in a composite object to have automatically continuity for these boundaries and leave the assembly mode for the interactions between composite objects
--
Good luck
Ivar
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Posted:
1 decade ago
The details about contact pairs were very helpful.
Please let me know when should I use identity pairs?
Thanks,
Sirisha
Please let me know when should I use identity pairs?
Thanks,
Sirisha
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Posted:
1 decade ago
Hi
Identity pairs is for use in COMSOL assembly model when you get many de-doubled boundaries, on some you could have contact pairs, but on others not. Then you need to establish CONTINUITY on them, that is for what you mostly use identity pairs. Also in multiphysics, a mechanical contact pair could have another definition in i.e. HT.
To avoid to be overhelmed with identiy pairs to be defined manually in V4 (for the time beeing) use the Composed Object in the geoemtry for all domains that would have continuity between them, you gain a lot of time like that.
And read carefully the doc, it takes time, I know, but it's worth it, and read carefully, each word counts, even the third time you read the doc you discover new things, because with all tese Physics there are really many many things to keep in mind, and they differ depending on which Physics your are linking
--
Good luck
Ivar
Identity pairs is for use in COMSOL assembly model when you get many de-doubled boundaries, on some you could have contact pairs, but on others not. Then you need to establish CONTINUITY on them, that is for what you mostly use identity pairs. Also in multiphysics, a mechanical contact pair could have another definition in i.e. HT.
To avoid to be overhelmed with identiy pairs to be defined manually in V4 (for the time beeing) use the Composed Object in the geoemtry for all domains that would have continuity between them, you gain a lot of time like that.
And read carefully the doc, it takes time, I know, but it's worth it, and read carefully, each word counts, even the third time you read the doc you discover new things, because with all tese Physics there are really many many things to keep in mind, and they differ depending on which Physics your are linking
--
Good luck
Ivar