Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
a question in the "electrochemical_polishing" example in comsol model library.
Posted Sep 13, 2012, 6:02 p.m. EDT Version 4.2a 2 Replies
Please login with a confirmed email address before reporting spam
Dear Ivar Kjelberg,
I am a comsol user, recently i am learning to use the "deformed geometry" function in comsol 4.2a,
There is a good example in the model library named "electrochemical polishing".
I don't undstand, in the "Deformed Geometry"-->"Prescribed Mesh Velocity 2" setting,
the "Prescribed y velocity" was setted as "-K*(-ec.nJ)" , the current density "ec.nJ" is normal to the surface,but the velocity in setting only has "y" component. Why?
"normal current density" should match the "normal deformed velocity", not just y component.
I was confused!!!
in "Prescribed Mesh Velocity 2" setting, the coordinate system can be changed from "global coordinate system" to "Boundary System 1 (sys1)", correspondingly, the "Prescribed y velocity" option will be switched to "Prescribed n velocity", it is the right normal velocity. Why comsol didn't do this in the above example for model library?
Looking forward to your reply!
Your help and information is deeply appreciated!!!
Sincerely,
Luyao
I am a comsol user, recently i am learning to use the "deformed geometry" function in comsol 4.2a,
There is a good example in the model library named "electrochemical polishing".
I don't undstand, in the "Deformed Geometry"-->"Prescribed Mesh Velocity 2" setting,
the "Prescribed y velocity" was setted as "-K*(-ec.nJ)" , the current density "ec.nJ" is normal to the surface,but the velocity in setting only has "y" component. Why?
"normal current density" should match the "normal deformed velocity", not just y component.
I was confused!!!
in "Prescribed Mesh Velocity 2" setting, the coordinate system can be changed from "global coordinate system" to "Boundary System 1 (sys1)", correspondingly, the "Prescribed y velocity" option will be switched to "Prescribed n velocity", it is the right normal velocity. Why comsol didn't do this in the above example for model library?
Looking forward to your reply!
Your help and information is deeply appreciated!!!
Sincerely,
Luyao
2 Replies Last Post Sep 17, 2012, 5:35 p.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hello
unfortunately I d onot have all COMSOl modules, so I cannot open that example, the best is to as "support", I can only guess, 1) a possibility is that your boundary is horizonal, hence its normal is along Y and nJ and y component of J are equal. 2) that there is an error and the coordinate used are not correctly selected, as you suggest.
Now boundary coordinates are nice to use in 2D, far trickier in 3D as you have still one normal but two tangential, not necesarily uiquely defined or not as one could expect, for all cases)
--
Good luck
Ivar
unfortunately I d onot have all COMSOl modules, so I cannot open that example, the best is to as "support", I can only guess, 1) a possibility is that your boundary is horizonal, hence its normal is along Y and nJ and y component of J are equal. 2) that there is an error and the coordinate used are not correctly selected, as you suggest.
Now boundary coordinates are nice to use in 2D, far trickier in 3D as you have still one normal but two tangential, not necesarily uiquely defined or not as one could expect, for all cases)
--
Good luck
Ivar
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Dear Ivar,
Thank you very much for your information!
Luyao
Thank you very much for your information!
Luyao