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-   -   thermal diffusivity (http://www.cfd-online.com/Forums/openfoam-programming-development/95278-thermal-diffusivity.html)

Tobi December 12, 2011 10:21

thermal diffusivity
 
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 ? ! ?

Tobi

akidess December 13, 2011 04:36

Yes, that's correct, the thermal diffusivity of water is roughly 1.4e-7 m2/s.

Tobi December 13, 2011 06:03

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.

akidess December 13, 2011 08:02

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?

Tobi December 13, 2011 11:00

Quote:

Originally Posted by akidess (Post 335665)
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.

Tobi


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