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.

Lagrange multiplier in axial symmetry

Please login with a confirmed email address before reporting spam

Hey Guys,

i am modelling a moving boundary interface (Stefan Problem), using the Lagrange multiplier T_lm from heat transfer analysis for prescribed normal mesh velocity in the deformed geometry physics.

The model is almost identical to the 2D Tin melting front example from Comsol library:
www.comsol.com/model/tin-melting-front-6234
except that I work in axial symmetry and my interface is perpendicular to the axis of symmetry.

When I solve, the Lagrange multiplier T_lm is always zero at r=0. I guess I am missing something fundamental here ? Does anyone have a hint for me ?

Thank you and Regards

--
______
Flanell

2 Replies Last Post 27 apr 2017, 05:40 GMT-4
COMSOL Moderator

Hello Flanell

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.


Please login with a confirmed email address before reporting spam

Posted: 7 years ago 18 apr 2017, 01:36 GMT-4
Hi Flanell,

In fact, the Lagrange multiplier T_lm should be in W/m2, but for symetric problems is in W/m. you should easily just use: T_lm [W/m^2]/(rho_Si*DelH*r*pi) instead of T_lm [W/m^2]/(rho_Si*DelH). In this case the Lagrange multiplier transfer from "per radius" to "per area (Pi*r*r*)"
Hi Flanell, In fact, the Lagrange multiplier T_lm should be in W/m2, but for symetric problems is in W/m. you should easily just use: T_lm [W/m^2]/(rho_Si*DelH*r*pi) instead of T_lm [W/m^2]/(rho_Si*DelH). In this case the Lagrange multiplier transfer from "per radius" to "per area (Pi*r*r*)"

Please login with a confirmed email address before reporting spam

Posted: 7 years ago 27 apr 2017, 05:40 GMT-4
Hi Amir,

thanks alot!

I figured it out alreday and it works like you said

Best

--
______
Flanell
Hi Amir, thanks alot! I figured it out alreday and it works like you said Best -- ______ Flanell

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.