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When Introducing Radiation -System becomes cooler?

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Old   March 2, 2009, 05:12
Default When Introducing Radiation -System becomes cooler?
  #1
Daniel
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Greetings,

I am using the Monte Carlo Model for my electric arc simulation. In reality i have Temperatures from 293 K (Gasfeed) to about 5000K (in the arc). I also introduce that to Cfxpre. Everything is working quite fine, but as a result i get a lot Locations were i have 210 -250 K, when i apply radiation?!?! This is physically not valid, why should a system cool down when considering Radiation. If i dont apply Radiaiton in the Simulation, i have no "Cooling" "Effect". Anyone knows the reason for this misscalculation ?
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Old   March 2, 2009, 06:34
Default Re: When Introducing Radiation -System becomes coo
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ganesh
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em not sure... , but may b u should check the radiation in detail...its of which type, if its irradiation den its okkk... but the other one would definately create problem.....
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Old   March 2, 2009, 06:42
Default Re: When Introducing Radiation -System becomes coo
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Daniel
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Well its thermal Radiation of course. and the System Shouldnt become cooler of it. The Solid regions must be heated up due to radiative Absorption. Surrounding Temperature is also at 293 K.

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Old   March 2, 2009, 07:35
Default Re: When Introducing Radiation -System becomes coo
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cfdguy
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Switching off the MC model, these cooler temperatures go away?

I recall that I had some similar issues in the past. But, instead of the radiation model, the low-Re wall treatment seemed to be not working properly for me. Switching to high-Re k-eps model these cooler temperatures were gone. Of course, I've had to make the mesh a bit coarser in the wall when switching to k-eps.

Good luck.

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Old   March 2, 2009, 08:51
Default Re: When Introducing Radiation -System becomes coo
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Daniel
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When i switch the model of, then i don't get any cooling. So the problem results definitly from the MC model.
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Old   March 2, 2009, 12:12
Default Re: When Introducing Radiation -System becomes coo
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cfdguy
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Then, which turbulence model are you using? Have you tried the standard k-eps?
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