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Old   August 2, 2006, 09:07
Default 2-D conjugate heat transfer
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Barbaros
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I am trying to model steady-state, 2-D (X-Y plane) conjugate heat transfer (CHT) with one fluid two solid domains. It's a simple channel flow type of thing. I am resolving the boundary layer around Y+=0.4 . In CFX you have to use a 3-D geometry to model a 2-D problem. I kept the depth (z-direction) small and only have two nodes in Z direction. For the flow domain I am using symmetry BC but should I use a adiabatic wall for the solid domains' walls in X-Y plane? I'd like to calculate how much of the heat flux goes to the fluid and solid domains. To verify the energy balance in a solid domain, for a steady state HT problem, if I area integrate the wall fluxes around the surfaces, should the result be zero? I am having some problems about this. Interfaces are used between the domains. Thanks for your help.
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Old   August 2, 2006, 10:10
Default Re: 2-D conjugate heat transfer
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Ram Dayal
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Dear Barbos I think you should take atleast 3 nodes in z-direction, bocz with 2 nodes each of them will be on the boundary walls which you are specifying as symmetry BC. Regarding solid domain wall BC both BC's are same mathematically. bye Ram Dayal
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Old   August 2, 2006, 17:34
Default Re: 2-D conjugate heat transfer
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Glenn Horrocks
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Hi Ram,

No, there is no need to use 3 nodes in the z direction for a 2D model. Two works just fine as there is no gradients in the z direction to resolve.

Glenn Horrocks
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Old   August 2, 2006, 17:37
Default Re: 2-D conjugate heat transfer
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Glenn Horrocks
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Hi,

On the high Z and low Z planes use symmetry boundaries.

Yes, an area integral of the total heat flux into the solid should give zero (if no heat sources and a steady state simulation). Also have a look at the imbalances in the simulation to check you have accurately balance the heat, often convergence on residuals alone is not sufficient for CHT simulations.

Glenn Horrocks
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Old   August 2, 2006, 21:01
Default Re: 2-D conjugate heat transfer
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Ram Dayal
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Hi Glenn Thanks for making it more clear for me. Bye Ram Dayal
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Old   August 3, 2006, 07:59
Default Re: 2-D conjugate heat transfer
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Barbaros
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Thanks for your response Glenn. I have a heat flux input for the bottom surface. Still heat_in should equal to heat_out since it's a steady state. But I'm getting 0.032W heat flux in vs 0.040W heat flux out. The difference is not acceptable. I kept the iteration up to 1500 but nothing changes.
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Old   August 3, 2006, 15:23
Default Re: 2-D conjugate heat transfer
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Barbaros
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Problem SOLVED!

I used double precision and it converged.
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Old   August 12, 2006, 01:45
Default Re: 2-D conjugate heat transfer *NM*
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SRINIVASULA REDDY PILLI
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