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How to change the default?
Posted Nov 14, 2010, 1:03 p.m. EST 3 Replies
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Does anybody know how we should change the axis of symmetry from Z to X or Y?
Also, how should we remove the default zero magnetic flux setting from external boundaries?
Also, how should we remove the default zero magnetic flux setting from external boundaries?
3 Replies Last Post Nov 15, 2010, 1:37 a.m. EST
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Posted:
1 decade ago
Hi
dependent variables names can be changed in the extension of the main physics nodes (if possible before filling in the model), but my advise is try to leave them "as is" and learn the COMSOL convention way (you can always rotate a geometry if it arrives in a "wrong" orientation.
True in 3.5 the main coordinate names x,y,z were accessed to, cannot remember where in 4 perhaps these are fixed !?
Because to learn how to use COMSOL you should exercice the examples of the doc and the library models, and these are with default COMSOL orientations and naming conventions, so it's as good to learn them from the beginning, no ?
To change an BC that i set by default, you must define a new one that overrides the previous one. Comsol V4 starts with a "coherent" set of BC's, you can always add new BC node, and if applicable it will "override" a previously defined condition
--
Good luck
Ivar
dependent variables names can be changed in the extension of the main physics nodes (if possible before filling in the model), but my advise is try to leave them "as is" and learn the COMSOL convention way (you can always rotate a geometry if it arrives in a "wrong" orientation.
True in 3.5 the main coordinate names x,y,z were accessed to, cannot remember where in 4 perhaps these are fixed !?
Because to learn how to use COMSOL you should exercice the examples of the doc and the library models, and these are with default COMSOL orientations and naming conventions, so it's as good to learn them from the beginning, no ?
To change an BC that i set by default, you must define a new one that overrides the previous one. Comsol V4 starts with a "coherent" set of BC's, you can always add new BC node, and if applicable it will "override" a previously defined condition
--
Good luck
Ivar
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Posted:
1 decade ago
Thank you for the reply.
Regarding the second question: the situation is that I want to calculate the magnetic field on the surface of a air sphere around a small permanent magnet in the sphere's center. But, because there is this magnetic insulation on exterior boundaries by default, I can't. Could you be a little more specific about how exactly should I remove this condition? Because when I add Magnetic Potential to the mfnc and manually select my boundaries the default scalar potential is again zero? I don't think that I should know the value of the field before the solver is run. Should I? I mean this is the very question I'm using the Comsol to solve in the first place? Could you explain more specifically how I should remove this boundary condition?
Thanks
Regarding the second question: the situation is that I want to calculate the magnetic field on the surface of a air sphere around a small permanent magnet in the sphere's center. But, because there is this magnetic insulation on exterior boundaries by default, I can't. Could you be a little more specific about how exactly should I remove this condition? Because when I add Magnetic Potential to the mfnc and manually select my boundaries the default scalar potential is again zero? I don't think that I should know the value of the field before the solver is run. Should I? I mean this is the very question I'm using the Comsol to solve in the first place? Could you explain more specifically how I should remove this boundary condition?
Thanks
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Posted:
1 decade ago
Hi
I'm not fully following you now, if you have a magnet surrounded by a sphere then the magnetic field should be "0" on the external border, otherwise how can you solve your case, and if not "0" what should it be ?
The sphere needs to be large enough so that the field has passed "close" to "0".
To make this sphere finite: have two spheres in slightly inside the other, and put an infinite element BC on the external shell, then you field lines would become more "as expected" and you can calculate the field on the internal sphere with a resonnable precision.
Still you should play a little with the sizes to get a reasonnable space to have your flux lines looping around in a "natural" way
--
Good luck
Ivar
I'm not fully following you now, if you have a magnet surrounded by a sphere then the magnetic field should be "0" on the external border, otherwise how can you solve your case, and if not "0" what should it be ?
The sphere needs to be large enough so that the field has passed "close" to "0".
To make this sphere finite: have two spheres in slightly inside the other, and put an infinite element BC on the external shell, then you field lines would become more "as expected" and you can calculate the field on the internal sphere with a resonnable precision.
Still you should play a little with the sizes to get a reasonnable space to have your flux lines looping around in a "natural" way
--
Good luck
Ivar