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Multiphase flow, water droplet simulation
Posted Jun 16, 2010, 8:12 p.m. EDT 4 Replies
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I tried to simulate a micrometer scale (e.g., diameter=20 micrometer) water droplet falling in air using phase field method. The simulation results are very strange: (1) water droplet will suspend in air and (2) it's volume is deceased (i.e., mass is not conserved). Anyone can suggest a solution?
It seems that with a correct setting of surface tension coefficient of 0.073N/m, the model predicts a very very large surface tension force (~10^9 N/m^3) for microscale water droplets. I have to dramatically decrease the surface tension coefficient (which is not physical) in order to simulate a falling water droplet.
Any suggesions/comments are welcome. thanks.
It seems that with a correct setting of surface tension coefficient of 0.073N/m, the model predicts a very very large surface tension force (~10^9 N/m^3) for microscale water droplets. I have to dramatically decrease the surface tension coefficient (which is not physical) in order to simulate a falling water droplet.
Any suggesions/comments are welcome. thanks.
4 Replies Last Post Jun 22, 2010, 9:06 a.m. EDT
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Posted:
1 decade ago
anyboday can give some suggestions? thanks.
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Posted:
1 decade ago
Hi
With droplet movement (or an enclosed shape movement), I have the same problems that the mass is never conserved. I tried all ways, but no success. This is a very common problem and is reported several times on this forum. By the way, Fluent is much better in this and you get a perfect solution, as it employes VOF method-presently not available in COMSOL.
I have also contacted support but the tricks they told could not resolve the issue. Sorry, but still this is an open issue!
Regards
Naveed
With droplet movement (or an enclosed shape movement), I have the same problems that the mass is never conserved. I tried all ways, but no success. This is a very common problem and is reported several times on this forum. By the way, Fluent is much better in this and you get a perfect solution, as it employes VOF method-presently not available in COMSOL.
I have also contacted support but the tricks they told could not resolve the issue. Sorry, but still this is an open issue!
Regards
Naveed
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Posted:
1 decade ago
Hi Naveed,
Thank you very much for your reply. By the way, have you encountered the unphysically large surface tension force issue?
Thank you very much for your reply. By the way, have you encountered the unphysically large surface tension force issue?
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Posted:
1 decade ago
Hi Jie
I did not calculated the surface tension force, I assume you will need a circumferential length (which is not well defined-as the droplet looses its mass and changes shape). What i did notice is there are instabilities occuring causing droplet break-up and mass loss!
Regards
Naveed
I did not calculated the surface tension force, I assume you will need a circumferential length (which is not well defined-as the droplet looses its mass and changes shape). What i did notice is there are instabilities occuring causing droplet break-up and mass loss!
Regards
Naveed