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natural convection problem for a CHT problem

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Old   June 9, 2007, 11:30
Default natural convection problem for a CHT problem
  #1
Se-Hee
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Hi! All,

I am trying to solve a conjugate heat transfer problem which strongly depends on the natural convection problem. Here, I cannot handle this problem with CFX. At first, I'd like to know how much my problem is difficult. Here is my problem as follows:

1) The long cylindrical enclosed tank is located along with z-axis. There are three electric wires, paralleling with z-axis, with triangular distribution inside tank.

2) When the electric current flows through the wires, the heat source can be generated by the Joule's heat law. Then the heat will be transferred to the tank through the gas by the thermal-convection flow. Finally, the air will be warmed on the tank surface, which is already heated by the thermal-convection flow generated by the Joule's heat source of three wires. All convection phenomena are natural convection.

In CFX, the flows of gas and air are not correct. The usual wire temperature is around 80 Celsius degree. The temperature of conductor is good agreement with my experiments, but the others are not. The temperature of tank fluctuates. How can I make it converge? And do I need to use any turbulent model? If so, would you recommend it? I'd like to welcome any comments and discussions.

Thanks, Se-Hee

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Old   June 9, 2007, 11:46
Default Re: natural convection problem for a CHT problem
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Joe
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"In CFX, the flows of gas and air are not correct.

Never, ever make a statement like that without providing proof that you have followed good numerical quality control procedures e.g. various grid/time independance tests.

http://www.ercoftac.org/index.php?id=77 https://pronet.wsatkins.co.uk/marnet...ations/bpg.pdf

etc.
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Old   June 10, 2007, 06:29
Default Re: natural convection problem for a CHT problem
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Se-Hee
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Thanks, Joe. Your information will be very helpful for my CFD study. Most probably, I think that the incorrect results were obtained from my faults in CFX setup. But, it looks very difficult problem for me.

Now, I am reading the document file of which I could download from the website you told me.

Se-Hee.
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