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Conjugate Heat Transfer at a pipe

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Old   August 12, 2009, 05:00
Default Conjugate Heat Transfer at a pipe
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Andi
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I want to simulate a conjugate heat transfer at a pipe but I do not know how to set the boundary conditions with Ansys Cfx Pre .
At the inlet of the pipe there is air with 350 K and a pressure of 1,2 bar and at the outlet of the pipe there should be a pressure of 1 bar. Outside the pipe (external surface) there should be a temperature of 293 K.
I have created a Domain Interface between the solid and the fluid domain.
With CFX Post I was able to see a temperature distribution within the fluid domain (in the pipe) but not in the solid domain of the pipe.
Does someone know which parameters I have to set in ANSYS Cfx Pre to get the temperature distribution in the solid domain of the pipe?

Thank you in advance,

Andi
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Old   August 12, 2009, 07:07
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Hi,

The timescales of the temperature in the pipe and the flow are likely to be different by orders of magnitude. That is to say the fluid flow will settle down in under a second but the pipe will take hours to come to a steady temperature.

So: Are you sure you have run it for long enough to get the pipe temperature to move significantly? If steady state are you using a solid timescale factor? Are you sure your simulation is converged? CHT simulations really need convergence on residuals AND imbalances to ensure convergence.

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Old   August 13, 2009, 04:57
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Hi,

I increased the solid timescale, now it works

Andi
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Old   August 13, 2009, 06:21
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Glenn Horrocks
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Hi,

You really need to use imbalances as a convergence critereon for these type of simulations. If you were using imbalances then you would have known that your first go had not converged.

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Old   August 17, 2009, 03:24
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Sir can we consider only fluid domain (considering inner dimensions of tube) and assuming canstant wall temp condition on outerwall... so there is no need of FSI and no question of steady state... am i right
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Old   August 17, 2009, 08:54
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If you are asking whether constant temperature boundary conditions can be applied, the answer is yes. I don't know what you mean about steady state, you will have to make the question clearer.
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