# Discussion Forum

## relative permeability as a function of mf.Hz and solid.sz

 Topics: 4.2a, Materials and functions, Physics, Solving, 4.0
RSS feed   |   Turn on email notifications   |   4 Replies   Last post: April 11, 2012 10:34pm UTC

Behrooz Rezaeealam

February 16, 2011 5:55am UTC

relative permeability as a function of mf.Hz and solid.sz

Hi
I am trying to define the relative permeability as a function of mf.Hz and solid.sz ( magnetic and structure application modes) using interpolation function as sectionwise file and calling it for example:
hsmu11=hsmu(mf.Hz[m/A],solid.sz[m^2/N])
However I face an error like this:

Circular variable dependency detected.
- Variable: mod1.hsmu11
- Geometry: 1
- Domain: 3

also i was wondering if i am suppoed to define the sequence of solutions for the two application modes, or it is considered automatically by itself, (for stationary case)

I would be grateful if you help me
Behrooz

Ivar Kjelberg

February 16, 2011 6:49am UTC in response to Behrooz Rezaeealam

Re: relative permeability as a function of mf.Hz and solid.sz

Hi

Indeed I would say that you must find a way to cut the circular reference: i.e to manually add a segregated solver sequence in your solution node

--
Good luck
Ivar

Gordon Freeman

February 21, 2011 1:22pm UTC in response to Behrooz Rezaeealam

Re: relative permeability as a function of mf.Hz and solid.sz

Hi
I am trying to define the relative permeability as a function of mf.Hz and solid.sz ( magnetic and structure application modes) using interpolation function as sectionwise file and calling it for example:
hsmu11=hsmu(mf.Hz[m/A],solid.sz[m^2/N])
However I face an error like this:

Circular variable dependency detected.
- Variable: mod1.hsmu11
- Geometry: 1
- Domain: 3

also i was wondering if i am suppoed to define the sequence of solutions for the two application modes, or it is considered automatically by itself, (for stationary case)

I would be grateful if you help me
Behrooz

Hello !

We have thermo-magnetic problem, and we have to define relative permeability depends on temperature and magnetic field (mur(T,H)), but we don't know how input this data.
Can you give us file with data for sectionwise interpolation ? We have the same problem and this examples would very usefull for us...

Thanks.

Behrooz Rezaeealam

February 21, 2011 11:56pm UTC in response to Gordon Freeman

Re: relative permeability as a function of mf.Hz and solid.sz

hello
i dont have a solved example untill now,
for sectionwise file format, you can find it inside the help,
the problem is the error of circular variable dependency, that can not be solved only by segregated steps, and actually you must know the formulation inside comsol to understand which parameter is accepted as an input, for example there is a problem with MUR(H,T), but probably there is no prblem with MUR(B,T),
H=magnetic intensity
B=flux density
good luck
behrooz

Giti Karimi

April 11, 2012 10:34pm UTC in response to Gordon Freeman

Re: relative permeability as a function of mf.Hz and solid.sz

Hi Gordon,
I work on thermo-magnetic too. Could you solve your problem which you mentioned here? I have the same problem. I have sent this e-mail for COMSOL support, and waiting for their reply;

Hello,
I need to define magnetization in the field as a function of magnetic field and temperature. I mean M=M(H,T). Since I have coupled "magnetic fields(mf)" and "Non-isothermal flow (nitf)", I don't have any problem with T, but it seems that I can not use H inside the "magnetic fields(mf)" module. I've got error as "Circular variable dependency detected", but I really need to do this. I would be so thankful if you can help me to know how I should do it.