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define sign scalar

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Old   June 20, 2012, 10:41
Default define sign scalar
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Jian Zhong
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Hi,

I set up a passive scalar. But when calculating, the negative values come out. Actually, the passive can not be negative. How to set the scalar to be sign type (only positive or zero value)?
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Old   June 20, 2012, 15:25
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Dear zx
you can do like this
rho == max(rho, rhoMin);
you should insert your value in rhoMin position.
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Old   June 21, 2012, 15:42
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Quote:
Originally Posted by niaz View Post
Dear zx
you can do like this
rho == max(rho, rhoMin);
you should insert your value in rhoMin position.
Many thanks. It works.
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Old   August 25, 2014, 15:06
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Jonas L. Ansoni
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Hello zx and niaz!!

I'm facing the same problem. I'm simulating the transport of a passive scalar (C) in a biphasic flow by interDymFoam and the values are negatives.
I created a new solver based on interDyFoam (interDyMScalarFoam.C) as can seen on the attached files. The solver works fine, however the values of the passive scalar are negatives.

I tried to use other numerical schemes such as suggested by Jasak on post #13, but without success.

You could give me more details of how you solved this problem. Where do you set rho == max(rho, rhoMin);?

Link to download the files (interDyMScalarFoam.C, C, fvSchemes, fvSolutions)
https://dl.dropboxusercontent.com/u/...onForum.tar.gz

Thanks a lot.
Attached Files
File Type: c interDyMScalarFoam.C (4.4 KB, 5 views)
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Old   August 25, 2014, 17:46
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Jian Zhong
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You may try C==max(C,0.0) after you solve the scalar transport equation.

Thanks,
Jian
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