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May 22, 2011, 08:41 
heat transfer coefficient as initial value

#1 
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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 

September 16, 2011, 08:52 

#2 
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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 

September 16, 2011, 10:16 

#3 
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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 

September 16, 2011, 10:21 

#4 
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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 

September 16, 2011, 19:25 

#5 
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Ok, thanks.
I look forward to your answer. Best Regards 

September 19, 2011, 06:57 

#6 
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I am now looking for this post ,
wallHeatFlux BC not constant after restart Also http://openfoamwiki.net/index.php/Contrib_groovyBC Playing with the groovyBC_2Way_coupling_001.tgz Hope find solution soon... Regards 

September 20, 2011, 04:11 

#7 
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Eelco van Vliet
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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*(TTamb); 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 

September 21, 2011, 20:58 

#8  
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Quote:
I will take ur advise carefully. Really Thanks a lot...Will get back to you if any problem.... Regards 

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