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How to set conditions for the internal boundaries?

Posted Jan 21, 2011, 11:21 p.m. EST Fluid & Heat, Geometry, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.2 12 Replies

Xiaoyi Yu
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How to set conditions for the internal boundaries?
12 Replies Last Post Jan 13, 2013, 11:25 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 22, 2011, 1:56 a.m. EST
Hi

by default t's continuity, if you need to set some specialphysics you mostly need t dissociate the up/down side (duplicate the boundary and these are the features of the COMSOL "assembly" mode

--
Good luck
Ivar
Hi by default t's continuity, if you need to set some specialphysics you mostly need t dissociate the up/down side (duplicate the boundary and these are the features of the COMSOL "assembly" mode -- Good luck Ivar
Xiaoyi Yu
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Posted: 1 decade ago Jan 22, 2011, 10:52 a.m. EST

Hi

by default t's continuity, if you need to set some specialphysics you mostly need t dissociate the up/down side (duplicate the boundary and these are the features of the COMSOL "assembly" mode

--
Good luck
Ivar


Hi,
You mean in the "Geometry --- Form Union" interface, I should choose "Form an assembly" instead of "Form a union" in the Finalization method option?
Thank you!
[QUOTE] Hi by default t's continuity, if you need to set some specialphysics you mostly need t dissociate the up/down side (duplicate the boundary and these are the features of the COMSOL "assembly" mode -- Good luck Ivar [/QUOTE] Hi, You mean in the "Geometry --- Form Union" interface, I should choose "Form an assembly" instead of "Form a union" in the Finalization method option? Thank you!
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 22, 2011, 12:39 p.m. EST
Hi

if you use frm assembly, then all common boundaries are duplicated and no "continuity are assumed, you must define all the identity pairs, and apply the continuity specifically.

For complex geoemtries with many domains and boundaries, where only a few needs te assembly capability, you should group the main objects witha n union or composite geoemtry (which is the classical CAD "assembly" function) not to confuse with COSMOL "entity assembly" mode

--
Good luck
Ivar
Hi if you use frm assembly, then all common boundaries are duplicated and no "continuity are assumed, you must define all the identity pairs, and apply the continuity specifically. For complex geoemtries with many domains and boundaries, where only a few needs te assembly capability, you should group the main objects witha n union or composite geoemtry (which is the classical CAD "assembly" function) not to confuse with COSMOL "entity assembly" mode -- Good luck Ivar
santhosh Boppa
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Posted: 1 decade ago Feb 8, 2011, 6:22 a.m. EST
Hi Ivar,
I have previously worked on comsol 3.5a version and recently updated it to 4.1 version. My problem is how do i plot the graph above or below a boundry like v use up(ec.normE) or down(ec.normE) in 3.5a version.

-thanks in advance
santhosh
Hi Ivar, I have previously worked on comsol 3.5a version and recently updated it to 4.1 version. My problem is how do i plot the graph above or below a boundry like v use up(ec.normE) or down(ec.normE) in 3.5a version. -thanks in advance santhosh
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 8, 2011, 10:41 a.m. EST
Hi

I believe you will find some goodies in the Results right click Plot "More" and sub menus therein

--
Good luck
Ivar
Hi I believe you will find some goodies in the Results right click Plot "More" and sub menus therein -- Good luck Ivar
Catharina Hoff
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Posted: 1 decade ago Mar 21, 2012, 11:41 a.m. EDT
Hi!

I still don't understand how to set the conditions for the internal boundaries.

I want to do a 2D-plot (in COMSOL 4.2). My geometry consists in short of two circles, one inside the other, where I have an inflow through a part of the outermost circle and I want the outflow to go through whole of the inner circle. However, this I cannot do as the boundary of the inner circle appear as "not applicable" in the Boundary Selection of the outflow. Under Geometry I formed an assembly with imprints and pairs created.

What do I have to do to remove the "not applicable" and be able to let the outflow go through the inner circle?

Thank you for your help!

Hi! I still don't understand how to set the conditions for the internal boundaries. I want to do a 2D-plot (in COMSOL 4.2). My geometry consists in short of two circles, one inside the other, where I have an inflow through a part of the outermost circle and I want the outflow to go through whole of the inner circle. However, this I cannot do as the boundary of the inner circle appear as "not applicable" in the Boundary Selection of the outflow. Under Geometry I formed an assembly with imprints and pairs created. What do I have to do to remove the "not applicable" and be able to let the outflow go through the inner circle? Thank you for your help!
Pu
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Posted: 1 decade ago Mar 21, 2012, 1:13 p.m. EDT
It seems I can do this by defining two subdomain variables on two sides of an internal boundary. The two subdomain variables are automatically available as variables on the boundary. Then boundary conditions can be imposed as a constraint.

Do u think if I'm right or wrong? Thanks for pointing out if I'm wrong.
It seems I can do this by defining two subdomain variables on two sides of an internal boundary. The two subdomain variables are automatically available as variables on the boundary. Then boundary conditions can be imposed as a constraint. Do u think if I'm right or wrong? Thanks for pointing out if I'm wrong.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Mar 21, 2012, 1:54 p.m. EDT
Hi

you cannot have an outflow or inflow on an internl boundary with the same physics applying on bothe domains/sides, as then you have a continuation, and these conflict.

So you need to remove the continuity and or split the physics, but this depends on the type of BCs, as some are exclusive, others contributive

--
Good luck
Ivar
Hi you cannot have an outflow or inflow on an internl boundary with the same physics applying on bothe domains/sides, as then you have a continuation, and these conflict. So you need to remove the continuity and or split the physics, but this depends on the type of BCs, as some are exclusive, others contributive -- Good luck Ivar
Tee Din Chai
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Posted: 1 decade ago Mar 22, 2012, 1:24 a.m. EDT

Hi

by default t's continuity, if you need to set some specialphysics you mostly need t dissociate the up/down side (duplicate the boundary and these are the features of the COMSOL "assembly" mode

--
Good luck
Ivar



if i have a PCF structure, so, how should i set the internal boundaries?
is it by default, the internal boundaries was set?
Do yo know why the result from Matlab (mphplot(model,'pg1')) is different from calculate from "[sz,ndofs,list,name,type]=mphgetp(model,'solname','sol1');" ?
thx
[QUOTE] Hi by default t's continuity, if you need to set some specialphysics you mostly need t dissociate the up/down side (duplicate the boundary and these are the features of the COMSOL "assembly" mode -- Good luck Ivar [/QUOTE] if i have a PCF structure, so, how should i set the internal boundaries? is it by default, the internal boundaries was set? Do yo know why the result from Matlab (mphplot(model,'pg1')) is different from calculate from "[sz,ndofs,list,name,type]=mphgetp(model,'solname','sol1');" ? thx
Catharina Hoff
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Posted: 1 decade ago Mar 22, 2012, 7:01 a.m. EDT
Thank you, but how do I then remove the continuity and/or split the physics?



Hi

you cannot have an outflow or inflow on an internl boundary with the same physics applying on bothe domains/sides, as then you have a continuation, and these conflict.

So you need to remove the continuity and or split the physics, but this depends on the type of BCs, as some are exclusive, others contributive

--
Good luck
Ivar


Thank you, but how do I then remove the continuity and/or split the physics? [QUOTE] Hi you cannot have an outflow or inflow on an internl boundary with the same physics applying on bothe domains/sides, as then you have a continuation, and these conflict. So you need to remove the continuity and or split the physics, but this depends on the type of BCs, as some are exclusive, others contributive -- Good luck Ivar [/QUOTE]
Tee Din Chai
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Posted: 1 decade ago Mar 22, 2012, 8:22 a.m. EDT
hi,Ivar

if i have a complex structure( photonic crystal fiber), should i set any internal boundaries?
or, i can neglect it since by default the internal boundaries is there already...?
hi,Ivar if i have a complex structure( photonic crystal fiber), should i set any internal boundaries? or, i can neglect it since by default the internal boundaries is there already...?
Hadi Afrouzi
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Posted: 1 decade ago Jan 13, 2013, 11:25 p.m. EST

HI
I have this problem also, I want to do a 2D-plot (in COMSOL 4.2).
I want set the internal boundary as a continuity , but it appear as "not applicable" , so it is set by default or we can remove " not applicable " and set the boundary as a continuity?

Any help would be appreciated.

HI I have this problem also, I want to do a 2D-plot (in COMSOL 4.2). I want set the internal boundary as a continuity , but it appear as "not applicable" , so it is set by default or we can remove " not applicable " and set the boundary as a continuity? Any help would be appreciated.

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