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Hall Effect Sensor

Posted Jul 3, 2012, 5:46 a.m. EDT Low-Frequency Electromagnetics Version 4.2a, Version 5.2, Version 5.2a 10 Replies

Hadi Hei
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Hi,
i working with COMSOL 4.2a and i have problem about Hall effect...
my problem is:
- for weak Constraint if i use Constraint expression : shlag(2,'lm') my model couldn't solve!!!! and bring an error that:
------------------------------------------------------------------------------------------------------------------------
Syntax error in expression.
- Expression: -shlag(2,'lm')*test(mod1.lm)-test(shlag(2,'lm'))*mod1.lm
------------------------------------------------------------------------------------------------------------------------
i don't know why? please help me!
10 Replies Last Post Aug 7, 2017, 10:33 a.m. EDT
Hadi Hei
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Posted: 1 decade ago Jul 3, 2012, 11:38 a.m. EDT
Please reply me!
i think the problem is from weak constraint! how can i adjust it?
Please reply me! i think the problem is from weak constraint! how can i adjust it?
Hadi Hei
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Posted: 1 decade ago Jul 5, 2012, 10:37 a.m. EDT
Why do I feel like NOBODY can help me?
Why do I feel like NOBODY can help me?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jul 6, 2012, 2:57 a.m. EDT
Hi

I do not believe it's NOT that we do not want to help, but rather that we do not understand the question correctly, or exactly what in your model is not working.

--
Good luck
Ivar
Hi I do not believe it's NOT that we do not want to help, but rather that we do not understand the question correctly, or exactly what in your model is not working. -- Good luck Ivar
Hadi Hei
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Posted: 1 decade ago Jul 6, 2012, 3:15 a.m. EDT
Dear Ivar,
Hi! many thanks for your attention! i attached my model,
my problem is:
if i use "weak Constraint", my model couldn't solve!!!! and bring an error below:
------------------------------------------------------------------------------------------------------------------------
Failed to find a solution for the initial parameter.
Singular matrix.

There are 364 void equations (empty rows in matrix) for the variable mod1.lm.
at coordinates: (0.01,0.003), (0.00966667,0.003), (0.00983333,0.003), (0.01,0.00263238), (0.01,0.00281619), ...
and similarly for the degrees of freedom (empty columns in matrix).
Returned solution is not converged.
------------------------------------------------------------------------------------------------------------------------
i don't know why?
Dear Ivar, Hi! many thanks for your attention! i attached my model, my problem is: if i use "weak Constraint", my model couldn't solve!!!! and bring an error below: ------------------------------------------------------------------------------------------------------------------------ Failed to find a solution for the initial parameter. Singular matrix. There are 364 void equations (empty rows in matrix) for the variable mod1.lm. at coordinates: (0.01,0.003), (0.00966667,0.003), (0.00983333,0.003), (0.01,0.00263238), (0.01,0.00281619), ... and similarly for the degrees of freedom (empty columns in matrix). Returned solution is not converged. ------------------------------------------------------------------------------------------------------------------------ i don't know why?

Attachments:

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jul 6, 2012, 3:38 a.m. EDT
Hi

Why not check again tha all domains have materials defined, for me you miss a material and related physicsal constants, hence the error

--
Good luck
Ivar
Hi Why not check again tha all domains have materials defined, for me you miss a material and related physicsal constants, hence the error -- Good luck Ivar
Hadi Hei
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Posted: 1 decade ago Jul 6, 2012, 3:53 a.m. EDT
Hi,
thanks, ok, i define copper for contacts, and also i put "shlag(2,'lm')" in constraint expression!
but it bring error yet!!!
strange for me is, when i disable "weak constraint" it working!
would you please find attachment...
Hi, thanks, ok, i define copper for contacts, and also i put "shlag(2,'lm')" in constraint expression! but it bring error yet!!! strange for me is, when i disable "weak constraint" it working! would you please find attachment...

Attachments:

Christian Nadell
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Posted: 7 years ago Jan 13, 2017, 3:48 p.m. EST
I realize this thread has been dormant for a while, but someone may still find a working version of the simulation useful, so my attempt is attached.

I disabled the weak constraint, as I'm not sure what the physical purpose is in this case... all of the geometric boundaries have conditions assigned via other nodes.

schlag seems to be an outdated function used to define a Lagrange shape function (see page 26, www.mscs.dal.ca/cluster/manuals/comsol/mlinterface.pdf) and is generally no longer used in the current version of comsol. Basically it's been replaced by the Discretization drop-down menu for weak constraint nodes.

As far as this particular simulation goes (opening it in 5.2a), there was a problem for me with the current conservation nodes' domain selection. Current Conservation 2 should be applied to the large silicon rectangle in the middle only, as it's here we'd like to implement the effective conductivity; everywhere else, the isotropic conductivity should be employed.

All in all, a neat little demonstration of modeling a Lorentz force without using a Lorentz Velocity Node (see AC/DC's mef module).
I realize this thread has been dormant for a while, but someone may still find a working version of the simulation useful, so my attempt is attached. I disabled the weak constraint, as I'm not sure what the physical purpose is in this case... all of the geometric boundaries have conditions assigned via other nodes. schlag seems to be an outdated function used to define a Lagrange shape function (see page 26, http://www.mscs.dal.ca/cluster/manuals/comsol/mlinterface.pdf) and is generally no longer used in the current version of comsol. Basically it's been replaced by the Discretization drop-down menu for weak constraint nodes. As far as this particular simulation goes (opening it in 5.2a), there was a problem for me with the current conservation nodes' domain selection. Current Conservation 2 should be applied to the large silicon rectangle in the middle only, as it's here we'd like to implement the effective conductivity; everywhere else, the isotropic conductivity should be employed. All in all, a neat little demonstration of modeling a Lorentz force without using a Lorentz Velocity Node (see AC/DC's mef module).

Attachments:

Mauricio Mendoza
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Posted: 7 years ago Aug 6, 2017, 12:16 p.m. EDT
Hi Christian.
Is there a possibility to have your Hall effect sensor simulation in COMSOL 5.2 ?

Thanks.

Ma Men.
Hi Christian. Is there a possibility to have your Hall effect sensor simulation in COMSOL 5.2 ? Thanks. Ma Men.
Wajid Ali
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Posted: 7 years ago Aug 7, 2017, 2:34 a.m. EDT
I am sorry for interruption with my question but I tried from three months continuously to get the answer or any help that how to apply a constant/uniform M.Field in wave optics physics to check the effect on scattering cross section of gold nano sphere.




Please help me



Best
Ali
I am sorry for interruption with my question but I tried from three months continuously to get the answer or any help that how to apply a constant/uniform M.Field in wave optics physics to check the effect on scattering cross section of gold nano sphere. Please help me Best Ali
Christian Nadell
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Posted: 7 years ago Aug 7, 2017, 10:33 a.m. EDT
Hey Ma Men,

Perhaps the instructions here (evgeni.org/oldfish/Top_nine_hints_for_working_with_Comsol#What_this_allows_you_to_do) or here
(femlab_users.yahoogroups.narkive.com/Cf9oJliO/comsol-users-how-to-open-a-file-made-with-a-new-version-with-the-previous-one)
could be of use. I don't know much about transferring models between versions of Comsol, but check it out, there may be an easy way.

Best,
Christian
Hey Ma Men, Perhaps the instructions here (http://evgeni.org/oldfish/Top_nine_hints_for_working_with_Comsol#What_this_allows_you_to_do) or here (http://femlab_users.yahoogroups.narkive.com/Cf9oJliO/comsol-users-how-to-open-a-file-made-with-a-new-version-with-the-previous-one) could be of use. I don't know much about transferring models between versions of Comsol, but check it out, there may be an easy way. Best, Christian

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