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Convergence issues with level-set conservative form

Posted 30.04.2012, 14:03 GMT-4 Fluid & Heat, Microfluidics, Mesh Version 4.3b 9 Replies

Mranal Jain
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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 07.01.2019, 08:41 GMT-5
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Hello Mranal Jain

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Osameh Ghazian
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Posted: 1 decade ago 17.08.2012, 09:50 GMT-4
I have the same problem.
I have the same problem.
Haishui huang
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Posted: 1 decade ago 18.10.2012, 12:23 GMT-4
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
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Posted: 1 decade ago 24.07.2013, 14:16 GMT-4
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
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Posted: 1 decade ago 07.11.2013, 08:23 GMT-5
Hi

Could anyone solve the problem!!!

Please help !!!
Hi Could anyone solve the problem!!! Please help !!!
Amin Kazemi
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Posted: 1 decade ago 11.07.2014, 12:48 GMT-4
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
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Posted: 1 decade ago 30.10.2014, 03:32 GMT-4
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
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Posted: 6 years ago 07.11.2018, 03:47 GMT-5

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
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Posted: 6 years ago 12.11.2018, 21:33 GMT-5
Updated: 6 years ago 12.11.2018, 21:33 GMT-5

HI, Mranal Do you know how to do now?

Thanks

HI, Mranal Do you know how to do now? Thanks
Abba Abubakar
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Posted: 6 years ago 07.01.2019, 08:41 GMT-5

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

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