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Boundary Conditions for an Assembly

Posted May 11, 2011, 11:23 a.m. EDT Version 4.2 3 Replies

Prisca Marianelli
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Hi everyone,

I am working with an assembly because the geometry is quite complex and it won't work otherwise.
As far as I have understood, I have to create pairs, so that the source and the destination domains are detected, in order to impose continuity across the borders of the two domains. To make Comsol do this automatically, I have to click on Draw > Create Pairs.

Then I want to specify the boundary conditions and in my case they have to be 'continuity'.
However, this is not available, because the boundaries are considered external.

If instead I choose one by one the source and the destination domains within my geometry, with Physics > Identity Pairs > Identity Boundary Pairs, then I've more choice for their boundary conditions. Since the object has many faces, the idea of picking them singularly freaks me out.

It's highly likely that I'm missing the real 'philosophy' of the identity pairs.
Can anyone give some suggestions?

Thank you in advance.

Prisca M
3 Replies Last Post May 30, 2011, 12:57 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 11, 2011, 11:38 a.m. EDT
Hi

indeed I believe there is a slight misunderstanding there. Now I havent used 3.5 for a loooong time ;) But i seem to remember that from the moment you select Geometry Create Identity pairs, they are all assembled as "continuity.

You must still in the Boundary tab, select pair, select identity pairs and set "free" = no other boundary condition (if I remember right)

Then if a few are to be other types of pairs i.e. contact you must select them specifically and create + add contact pairs, that normally deselect r override (pls check) the previously defined identity pairs.

In V4.1, unfortunately, all pairs must be manually defined two by two, no "automatic all relevant = continuity does, yet, exist, most probably it will reappear in V4.2 we will see ;)

--
Good luck
Ivar
Hi indeed I believe there is a slight misunderstanding there. Now I havent used 3.5 for a loooong time ;) But i seem to remember that from the moment you select Geometry Create Identity pairs, they are all assembled as "continuity. You must still in the Boundary tab, select pair, select identity pairs and set "free" = no other boundary condition (if I remember right) Then if a few are to be other types of pairs i.e. contact you must select them specifically and create + add contact pairs, that normally deselect r override (pls check) the previously defined identity pairs. In V4.1, unfortunately, all pairs must be manually defined two by two, no "automatic all relevant = continuity does, yet, exist, most probably it will reappear in V4.2 we will see ;) -- Good luck Ivar
Jonathan Ford
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Posted: 1 decade ago May 26, 2011, 2:45 p.m. EDT
Hi Ivar,

I was just wondering if that change in contact pairs you just mentioned has taken affect in 4.2?

Thanks in advance!

Jonathan
Hi Ivar, I was just wondering if that change in contact pairs you just mentioned has taken affect in 4.2? Thanks in advance! Jonathan
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 30, 2011, 12:57 a.m. EDT
Hi

in V4.2 identity pairs are created by default, again ;)

Another thing to remember, if you group your geometry with composite object or unions, then the "assembly" mode will only consider the external boundaries of these composed objects, and use standard continuity on the internal boundaries, this reduces drastically the number of "pair" boundaries to handle, for more complex models

--
Good luck
Ivar
Hi in V4.2 identity pairs are created by default, again ;) Another thing to remember, if you group your geometry with composite object or unions, then the "assembly" mode will only consider the external boundaries of these composed objects, and use standard continuity on the internal boundaries, this reduces drastically the number of "pair" boundaries to handle, for more complex models -- Good luck Ivar

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