Menu

Discussion Forum

New Discussion
Filter

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 The information provided may be out of date.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.

Convergence issues with level-set conservative form

Posted Apr 30, 2012, 2:03 p.m. EDT Fluid & Heat, Microfluidics, Mesh Version 4.3b 9 Replies

Mranal Jain
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Hello Everyone,

I am trying level-set conservative form for droplet generation in flow focusing device. I have tried the following:

(a) non-conservative form: it converges well but mass conservation is an issue, droplet size keeps reducing with time and in some cases vanishes just before the outlet.

(b) conservative form: convergence problems; the error shown is 'may have reached singularity'

(c) I have tried finer meshes; smaller time steps with both conservative and non-conservative forms but same results as case (a) and (b)

(d) It looks like the level set parameters epsilon (related to interface thickness) and gamma (reinitialization parameters) could be the key but other than heuristics given in Comsol documentation, i have no clue about how to tune them. Though i tried few trial and error cases for tuning these parameters with no success.

Please share your experience/ thoughts/ suggestions about improving convergence or for suitable tuning of level set parameters.

Thanks in advance.
9 Replies Last Post Jan 7, 2019, 8:41 a.m. EST
COMSOL Moderator

Hello Mranal Jain

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.

Osameh Ghazian
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Aug 17, 2012, 9:50 a.m. EDT
I have the same problem.
I have the same problem.
Haishui huang
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Oct 18, 2012, 12:23 p.m. EDT
I have the same problem.
Who knows what is the physics meaning of reinitialization parameter?

Thanks
I have the same problem. Who knows what is the physics meaning of reinitialization parameter? Thanks
Adam Churchman
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jul 24, 2013, 2:16 p.m. EDT
For the last couple of months I have been attempted the same (in both 2D and 3D), with no luck.
Did you (or anyone else) ever manage to model this?
If so I would really appreciate some tips if you have any.
For the last couple of months I have been attempted the same (in both 2D and 3D), with no luck. Did you (or anyone else) ever manage to model this? If so I would really appreciate some tips if you have any.
Reza Safi
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Nov 7, 2013, 8:23 a.m. EST
Hi

Could anyone solve the problem!!!

Please help !!!
Hi Could anyone solve the problem!!! Please help !!!
Amin Kazemi
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jul 11, 2014, 12:48 p.m. EDT
I have the same problem. My geometry is a meniscus. I am working with phase field method. When I let the meniscus form, it moves upward continuously.
Here is my experience:

1) Make the mesh as small as possible.
2) Change the tuning parameters

Although both can solve the problem partially, the liquid spontaneous upward motion still exists but at a slower speed....

I've heard about "conservative form" in comsol. Does it mean the mass conservation? I tried it but I couldn't get my simulation converged. Does anybody have an idea?
I have the same problem. My geometry is a meniscus. I am working with phase field method. When I let the meniscus form, it moves upward continuously. Here is my experience: 1) Make the mesh as small as possible. 2) Change the tuning parameters Although both can solve the problem partially, the liquid spontaneous upward motion still exists but at a slower speed.... I've heard about "conservative form" in comsol. Does it mean the mass conservation? I tried it but I couldn't get my simulation converged. Does anybody have an idea?
Maziyar Mahmoodi
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Oct 30, 2014, 3:32 a.m. EDT
I suggest to reduce the time step in time dependent solver , also .
I suggest to reduce the time step in time dependent solver , also .
Qiang Wang
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 6 years ago Nov 7, 2018, 3:47 a.m. EST

I have some questions about mass conservation. I have try the conservative form in comsol. I couldn't get my simulation converged.

I have some questions about mass conservation. I have try the conservative form in comsol. I couldn't get my simulation converged.
Qiang Wang
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 6 years ago Nov 12, 2018, 9:33 p.m. EST
Updated: 6 years ago Nov 12, 2018, 9:33 p.m. EST

HI, Mranal Do you know how to do now?

Thanks

HI, Mranal Do you know how to do now? Thanks
Abba Abubakar
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 6 years ago Jan 7, 2019, 8:41 a.m. EST

Dear FriendS,

I have similar problem on shrinking droplets with level set, please can you share your experience/ thoughts/ suggestions on how to make model works ?

Sincerely appreciate

Dear FriendS, I have similar problem on shrinking droplets with level set, please can you share your experience/ thoughts/ suggestions on how to make model works ? Sincerely appreciate

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