# thermal diffusivity

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 December 12, 2011, 10:21 thermal diffusivity #1 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 2,025 Blog Entries: 6 Rep Power: 34 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 (20°C) 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

 December 13, 2011, 04:36 #2 Senior Member     Anton Kidess Join Date: May 2009 Location: Germany Posts: 1,280 Rep Power: 23 Yes, that's correct, the thermal diffusivity of water is roughly 1.4e-7 m2/s. __________________ *On twitter @akidTwit *Spend as much time formulating your questions as you expect people to spend on their answer.

 December 13, 2011, 06:03 #3 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 2,025 Blog Entries: 6 Rep Power: 34 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.

 December 13, 2011, 08:02 #4 Senior Member     Anton Kidess Join Date: May 2009 Location: Germany Posts: 1,280 Rep Power: 23 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? __________________ *On twitter @akidTwit *Spend as much time formulating your questions as you expect people to spend on their answer.

December 13, 2011, 11:00
#5
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Tobias Holzmann
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Quote:
 Originally Posted by akidess 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.

Tobi

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