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Old   December 13, 2010, 13:21
Default default contact angle
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Sandeep
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hello all,

For my two phase problem I have used interFoam to simulate a droplet spreading on a substrate. My question is, what is the default contact angle assumed by the interFoam solver. Some where I read that it uses 90degree CA. So, I did the my case by modifing a case described in multiphaseInterFoam solver with 90 degree contact angle. But the results are not same. Can anybody help me what woud be the reason.

Thanks
Sandeep
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Old   January 13, 2011, 03:41
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can anyone please reply to this message
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Old   January 13, 2011, 10:09
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Duong A. Hoang
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Hi,

You can set the static or dynamic contact angle boundary condition in 0/alpha1 like:

23 Wall1
24 {
25 type constantAlphaContactAngle;
26 limit gradient;
27 theta0 0;
28 value uniform 1;
29 }

There are a lot of posts in this forum discussing about those conditions.

Regards,

Duong
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Old   January 14, 2011, 04:51
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Hi Hoang,

Thanks for your reply. I think I did not make my question proper. Here is my question once again. Two simulate my 2 phase vof problem, I have used default dambreak example prblems available in both interform and multiphaseinterfoam solvers. If you look at the dam break example in multiphaseinterfoam solver, you can see 4 phases interacting between each other and you can see wall contact angle specified for all the phases. If you see same dam break example in interfoam solver, you can only see two phases and there were no contact angles mentioned in the 0/alpha file. So my question is the what is the value assumed by the interform for considering boundary condition?? Does it really considers contact angle as the boundary condition or is it considering any other boundary condition in interfoam?? As i am newbie to openfoam not able to look and find at the source code.

I hope this time i made my question more clear. Please let me know if you are stil confused.
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Old   January 21, 2011, 06:31
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Duong A. Hoang
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Hi,

In interfoam, since you have only two phase, then you only specify the contact angle once in alpha1 file. For your question, in dambreak case, at the wall they use zero gradient condition at the wall for alpha1. Then at the wall, alpha1 will equal to alpha1 at the cell next to the wall. And in my experience, that condition will generate 90 degree contact angle.

Hope it answer your question.

Regards,

Duong
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Old   January 21, 2011, 09:19
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Hi HOang,

Thanks for your reply. Well, actually I had done a case by modifying multiphasefoam dam break example to two phases and defining 90 degree contact angle. The results obtained by this solver are entirely different from the result obtained from interfoam. So what could be the probable reason.

Sandeep
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Old   January 24, 2011, 23:35
Default How do you define the contact angle?
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Charlie
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Did you define it as what Duong said?
Quote:
23 Wall1
24 {
25 type constantAlphaContactAngle;
26 limit gradient;
27 theta0 0;
28 value uniform 1;
29 }
can you show us how to modify the contact angle to 90 degrees?
BTW, do you define it as 90 or pi/2?
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Old   January 24, 2011, 23:52
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I have assigned 90 degrees not pi/2.
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