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Old   December 12, 2011, 10:21
Default thermal diffusivity
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Tobias Holzmann
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Hi all,

i 've implemented the temperaturfield and a temperature dependen saturation pressure on the interPhaseChangeFoam.

In the icoFoam tutorial in which the temperature is implemented there is a factor DT = 0,002

I ve read that DT = k / cp * rho.

if i wanna simulat water (20C) i ve to change that DT to 1,4e-7
is that correct?

I am not sure couse in the calmers report there is DT added with the value of 0,002 and water is the fluid ? ! ?

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Old   December 13, 2011, 04:36
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Yes, that's correct, the thermal diffusivity of water is roughly 1.4e-7 m2/s.
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Old   December 13, 2011, 06:03
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hey akidess,

thx for you answer.

In my case i vaporize water with a new myInterPhaseChangeFoam solver.

I added a temperatur dependen pSat and implemented the temperature field with the code:

Code:
{
fvScalarMatrix TEqn
(
fvm::ddt(T)
+ fvm::div(phi, T)
- fvm::laplacian(DT, T)
);
TEqn.solve();
}
Like the studentreport down in that link http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2011/

is that correct?

Couse if i set the DT from 0,002 to 1,4e-7 i get a better thermal flux in the fluid ??

I thought that the temperature flux is worser with 1,4e-7 than with 0,002 ?

Is that correct? Hope you understand what i am meaning.
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Old   December 13, 2011, 08:02
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Which student report? Provide a better link, so that I don't have to sift through the entire site.

What do you mean with a better thermal flux? Either it is physical, or it is not. Also, how can you neglect the release of latent heat in your phase change solver?
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Old   December 13, 2011, 11:00
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Quote:
Originally Posted by akidess View Post
Which student report? Provide a better link, so that I don't have to sift through the entire site.

What do you mean with a better thermal flux? Either it is physical, or it is not. Also, how can you neglect the release of latent heat in your phase change solver?


Hi, sorry for the link. Here is the student report http://www.tfd.chalmers.se/~hani/kur...ChangeFoam.pdf

I `ll place 2 videos today or tomorrow with the explanation of my problem.
thanks in advance.

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