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Solutions Missing/Geometry ordering(?)

Posted Apr 25, 2011, 2:38 p.m. EDT Low-Frequency Electromagnetics, Geometry, Studies & Solvers Version 4.1 3 Replies

Adam Steele
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Sometimes when I build geometry and then solve, the solution is missing within certain domains.

For example: let's say I have a few magnets in my model and a bigger cylinder surrounding all of them. Sometimes the solver will not find the fields in the regions between the magnets.


The problem occurs often, but in a totally inconsistent way so that it is difficult to know what ordering or whether just shutting down the program, or re-ordering where the outer boundary is placed in the geometry list is going to fix the problem.

I have attached a mph were the solver doesn't find the fields in one of the two iron pieces. by changing where the outer shield appears in the geometry list sometimes it won't find the b field in any of the air regions instead.

What causes this?

Thanks,
Adam

PS- I don't know if this is a hint as to what is causing this, but the piece within which there is no solution is the only thing that appears on the screen when I first open COMSOL, as soon as i click anywhere on the geometry list the other parts appear.

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3 Replies Last Post Apr 26, 2011, 2:52 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 25, 2011, 5:30 p.m. EDT
Hi

indeed something is messed up in your "Definition - View 1" Create a new one and delete View 1, for me it works thereafter (I did also a clear solution, clear mesh and reset but that was NOT enough ;)

--
Good luck
Ivar
Hi indeed something is messed up in your "Definition - View 1" Create a new one and delete View 1, for me it works thereafter (I did also a clear solution, clear mesh and reset but that was NOT enough ;) -- Good luck Ivar
Adam Steele
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Posted: 1 decade ago Apr 26, 2011, 11:20 a.m. EDT
I figured out what is happening. The view wasn't broken or anything. But if you 'hide' domains while viewing your geometry, then any 2D or 3D plots you make later will hide the solutions in these regions. Your 'delete and reform' solution worked because a new view by default doesn't hide any objects. My old solution of creating new elements or changing their order worked because when you create anew object often all of them get renumbered and what was in the hidden list can change.

I don't know if this behavior is intended, but given how often things need to be hidden when working with 3D geometries, its bound to be confusing for new users.
I figured out what is happening. The view wasn't broken or anything. But if you 'hide' domains while viewing your geometry, then any 2D or 3D plots you make later will hide the solutions in these regions. Your 'delete and reform' solution worked because a new view by default doesn't hide any objects. My old solution of creating new elements or changing their order worked because when you create anew object often all of them get renumbered and what was in the hidden list can change. I don't know if this behavior is intended, but given how often things need to be hidden when working with 3D geometries, its bound to be confusing for new users.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 26, 2011, 2:52 p.m. EDT
Hi

Yes I noticed the "hidden" node, but even after deleting it + refresh + update screen, I could not get all items on the screen, only after generating a new View I found all items back. So I ssupect there was something more.

when making "hidden views" I always make a new one, so the default view is a full view, as it changes at all times, all new plot are linked to it. Have you noticed that all main plot views are attached to a view, mostly via "automatic", but you can also manually tell COMSOL to use different views, i.e. have top, front and side views defined.

--
Good luck
Ivar
Hi Yes I noticed the "hidden" node, but even after deleting it + refresh + update screen, I could not get all items on the screen, only after generating a new View I found all items back. So I ssupect there was something more. when making "hidden views" I always make a new one, so the default view is a full view, as it changes at all times, all new plot are linked to it. Have you noticed that all main plot views are attached to a view, mostly via "automatic", but you can also manually tell COMSOL to use different views, i.e. have top, front and side views defined. -- Good luck Ivar

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