Menu

Discussion Forum

New Discussion
Filtern

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 The information provided may be out of date.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.

Floating potentials when solving Laplace equation

Posted 09.11.2015, 10:15 GMT-5 Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.3 5 Replies

Ari
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hi,

I have a question about floating potentials and overridden boundary conditions when solving Laplace equation. My system consists of a few metallic surfaces and some dielectric structures and I solve Laplace equation for the surrounding area using Dirichlet Boundary conditions on the metallic surfaces.

Firstly, the Dirichlet Boundary conditions are overridden by a default zero flux. Does it matter?
Secondly, as far as I understand, to get the right solution I have to change the boundary conditions on the dielectric surfaces into a floating potential otherwise a zero flux is applied to them by default .
What is the way around this issue?

Really appreciate any comment or insight!
5 Replies Last Post 09.11.2015, 17:01 GMT-5
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 09.11.2015, 10:48 GMT-5
Hello Ari,
There is a floating potential boundary condition available right out of the box in the AC/DC Module's and the MEMS Module's electrostatic physics interface.
Best regards,
Jeff
Hello Ari, There is a floating potential boundary condition available right out of the box in the AC/DC Module's and the MEMS Module's electrostatic physics interface. Best regards, Jeff
Ari
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 09.11.2015, 11:40 GMT-5
Hi Jeff,
Thanks a lot for your quick reply.
So, I have to set up the model with more generality instead of using "Laplace Equation (lpeq)". Also, it does mean that leaving the zero flux on the dielectrics is not a good idea since it changes the physics of my actual problem, right?
Best regards,
Ari
Hi Jeff, Thanks a lot for your quick reply. So, I have to set up the model with more generality instead of using "Laplace Equation (lpeq)". Also, it does mean that leaving the zero flux on the dielectrics is not a good idea since it changes the physics of my actual problem, right? Best regards, Ari
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 09.11.2015, 11:59 GMT-5
When you apply the floating potential boundary condition, it automatically overrides the default (which is zero charge) boundary condition.
Jeff
When you apply the floating potential boundary condition, it automatically overrides the default (which is zero charge) boundary condition. Jeff
Ari
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 09.11.2015, 13:11 GMT-5
Yes, it obviously does, but I'm a bit confused about when these overridden boundaries might become a concern. What do you think?
Best,
Ari
Yes, it obviously does, but I'm a bit confused about when these overridden boundaries might become a concern. What do you think? Best, Ari
Jeff Hiller COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 9 years ago 09.11.2015, 17:01 GMT-5
I am afraid I may not have understood your questions/concerns. I leave it to others to chime in.
Jeff
I am afraid I may not have understood your questions/concerns. I leave it to others to chime in. Jeff

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content