# what kind of boundary condition should I use

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June 6, 2012, 22:51
what kind of boundary condition should I use
#1
Member

zakir
Join Date: Nov 2011
Posts: 43
Rep Power: 8
Dear all
I am simulating an MHD problem .liquid metal flows in a rectangular duct with external magnetic field.Now I run into trouble with the boundary conditions.I attached my details step here:

Can you give me some suggestion about the boundary condition of phi(BC)?

Thank you!

zakir
Attached Images
 QQ??20120607104911.png (41.8 KB, 72 views)

 June 10, 2012, 08:08 #2 Member   zakir Join Date: Nov 2011 Posts: 43 Rep Power: 8 Does anyone can give me some suggestions?I am really in trouble with it. Thank you! zakir

 June 10, 2012, 13:44 #3 Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,125 Blog Entries: 39 Rep Power: 110 Greetings Zakir, OK, you mention the kind of problem you want to solve, but you haven't mentioned yet which solver you are trying to use! Best regards, Bruno __________________ OpenFOAM: FAQ | Getting started Forum: How to get help, to post code/output and forum guide What am I doing/planning: blog/wiki Read this before sending me PM

 June 11, 2012, 01:16 #4 Member   zakir Join Date: Nov 2011 Posts: 43 Rep Power: 8 Thanks for your attention. I use a solver I wrote myself.It contains the knowdge about finite area method and finite volume method.First I need solve the 3D electric potential equation all the fluid field with initial boundary condition.And then I have to solve a 2D electric potential equation (just like the file I have attached) on the boudary of fluid field. Then I need to use the solution of the 2D electric potential equation as the new boundary condition of solving 3D electric potential equation in the fluid field at the next time step. I wrote my solver just as the attached file. Have I expressed my point clearly? Thank you for your advice. zakir Last edited by zakir hussain; June 11, 2012 at 10:35.

June 11, 2012, 04:31
#5
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Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,045
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Quote:
 Originally Posted by zakir hussain Thanks for your attention. I use a solver I wrote myself.It contains the knowdge about finite area method and finite volume method.First I need solve the 3D electric potential equation all the fluid field with initial boundary condition.And then I have solve a 2D electric potential equation (just like the file I have attached) on the boudary of fluid field. Then I need to use the solution of the 2D electric potential equation as the new boundary condition of solving 3D electric potential equation in the fluid field at the next time step. I wrote my solver just as the attached file. Have I expressed my point clearly? Thank you for your advice. zakir
Please don't include the main point of your question in a Bitmap. It is not possible to search that using the search function of the MessageBoard and the answers are therefor useless for everyone who might have the same question.

What you want is a FAM to FVM-coupling right. Something like
Code:
```
volSurfaceMapping mapper(famField.mesh());

mapper.mapToVolume(famField,  fvmField.boundaryField());```
in your code copies the internal field of the famField to the appropriate patches of the fvmField (make sure the patches are of appropriate type ... fixedValue for instance)

June 11, 2012, 10:48
#6
Member

zakir
Join Date: Nov 2011
Posts: 43
Rep Power: 8
Quote:
 Originally Posted by gschaider What you want is a FAM to FVM-coupling right. Something like Code: ``` volSurfaceMapping mapper(famField.mesh()); mapper.mapToVolume(famField, fvmField.boundaryField());``` in your code copies the internal field of the famField to the appropriate patches of the fvmField (make sure the patches are of appropriate type ... fixedValue for instance)
yes, I have used the code you mentioned.But I don't know why it didn't calculate the 2D electric potential equation during a time step.The iteration number of solving 2D electric potential equation is zero.I doubt that I have applied the wrong initial boundary condition of electric potential (3D).Does the initial boundary conditions play that much important role during solving?
what kind of boundary condition should I use for electric potential (3D)?

regards!

zakir

June 12, 2012, 05:03
#7
Member

zakir
Join Date: Nov 2011
Posts: 43
Rep Power: 8
Does the initial boundary condition in 0 dictionary paly a role in every time step ? For example when solving the 3D electric potential equation ,does the inputing file of 3D electric potential in 0 dictionary have influence on the solving in every time step?

regards!

zakir
Attached Images
 QQ??20120612170301.png (4.3 KB, 9 views)

Last edited by zakir hussain; June 15, 2012 at 00:49.

 September 7, 2012, 08:33 #8 New Member   Peter L. Join Date: Sep 2012 Posts: 1 Rep Power: 0 Hi zakir hussein and others, which version of OF are you using? I was out of touch from OF for a few years, and it seems the the FAM is not part of OF-2.1! Any suggestions? It looks like you are using FAM, so I thought you could help... Thx, Peter

 September 7, 2012, 09:17 #9 Member   zakir Join Date: Nov 2011 Posts: 43 Rep Power: 8 Hi Peter As I know,The FAM only exists at OF-1.6.ext.I still have many problem about that.We can discuss together. regards! zakir

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