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-   -   heat transfer coefficient as initial value (http://www.cfd-online.com/Forums/openfoam/88626-heat-transfer-coefficient-initial-value.html)

 tH3f0rC3 May 22, 2011 08:41

heat transfer coefficient as initial value

Hi there,

I want to model the heat transfer between a hot fluid and a cold solid. Because the whole case has a lot of elements the calculation needs a lot of time.
So I thought about the following:

I will identify the heat transfer coefficient from an easy simulation which is solved very fast with the same properties.
Than I want to set the heat transfer coefficient as an initial value for the following calculation. Because in the following calculation only the solid has to be solved and no fluid is needed.

So my question is: Is it possible to set the heat transfer coefficient as an initial value / boundary condition in one of the heat transfer solvers?

Best Regards,
tH3f0rC3

 yipiyaya8 September 16, 2011 08:52

I hv also face the same problem...

My case is cooling hot plate with coolent air ...I have to input heat transfer coeff as initial value.
I dont know how to write it!

Kindly help
Thanks

 tH3f0rC3 September 16, 2011 10:16

My research has shown that it is not easily possible to set up the heat transfer coefficients with OpenFoam.
But it is easy to do this with Fluent.

If you or someone else know how to implement the heat transfer coefficients as boundary conditions to OpenFoam please let me know.

Best Regards,
tH3f0rC3

 yipiyaya8 September 16, 2011 10:21

Hm...

Perhaps i need to use initial T and mass flow rate as substitution of HTC...

Anyway i will try input HTC for now...I will tell u if i got it!

Regards:)

 tH3f0rC3 September 16, 2011 19:25

Ok, thanks.

Best Regards ;)

 yipiyaya8 September 19, 2011 06:57

I am now looking for this post ,
http://www.cfd-online.com/Forums/ope...r-restart.html

Also
http://openfoamwiki.net/index.php/Contrib_groovyBC

Playing with the
groovyBC_2Way_coupling_001.tgz

Hope find solution soon...;)

Regards

 eelcovv September 20, 2011 04:11

groovyBC is the way to go to impose heat transfer coefficients as a boundary condition for your temperature field. Just calculate in groovyBC the heatflux as qflux=hcof*(T-Tamb); where Tamb is a variable with you ambient temperature, hcof is a variable of the heat flux, and subsequently calculate the temperature gradient according to the post you are referering to (heat flux not constant). Bear in mind that the alphaEff should excist in your solver (i.e. is a field containing the effective heat diffusivity given by alphaEff=alpha+alphat, with alpha=lambda/rho Cp (molecular diffusivity), and alphat=nut/Prt with Prt=0.7 (turbulent prandtl number) for the turbulent diffusivity.
Good luck!
Regards
Eelco

 yipiyaya8 September 21, 2011 20:58

Quote:
 Originally Posted by eelcovv (Post 324797) groovyBC is the way to go to impose heat transfer coefficients as a boundary condition for your temperature field. Just calculate in groovyBC the heatflux as qflux=hcof*(T-Tamb); where Tamb is a variable with you ambient temperature, hcof is a variable of the heat flux, and subsequently calculate the temperature gradient according to the post you are referering to (heat flux not constant). Bear in mind that the alphaEff should excist in your solver (i.e. is a field containing the effective heat diffusivity given by alphaEff=alpha+alphat, with alpha=lambda/rho Cp (molecular diffusivity), and alphat=nut/Prt with Prt=0.7 (turbulent prandtl number) for the turbulent diffusivity. Good luck! Regards Eelco
Hi eelcovv,

I will take ur advise carefully. Really Thanks a lot...Will get back to you if any problem....

Regards:)

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