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Old   August 9, 2016, 03:26
Default Problem heat transfer CFX
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Mark T.
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Hi,

I'm new in CFX and currently simulating water flow in copper pipe heated by surrounding cladding. I received a following error in CFX Solver:

****** Notice ******
| The Wall Heat Transfer Coefficient written to the results file for
| any turbulent phase with heat transfer is based on the turbulent
| wall function coefficient. It is consistent with the Wall Heat Flux
| the wall temperature, and the Wall Adjacent Temperature
| (near-wall temperature). If you would like it to be based on a
| user-specified bulk temperature instead, please set the expert
| parameter "tbulk for htc = <value>".

There's no heat transfer calculation done in Solver plots. Can anyone help?
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Old   August 9, 2016, 06:13
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Glenn Horrocks
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It is not an error, it is a notice. It just says that if you want the heat transfer coefficient to be referenced to a fixed temperature (as it is for most engineering work) you can use the expert parameter described to do it. The default heat transfer coefficient is based on a estimated reference temperature which will cause problems if you wish to use the HTC to compare to published values.

If this is not relevant to you then you can ignore the notice.
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Old   August 9, 2016, 11:43
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Mark T.
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Thanks. I was curious, because heat transfer does not show results and the error was written in code.. May I kindly ask about possible failure reason regarding no heat flow reaction in model? Please see plot from solver in attachment.. I have put temperature gradient on cladding from where the heat moves towards pipe. I defined surfaces between solid-solid, liquid-solid. I have removed the pipe and modeled it instead both as thin layer and as thermal resistance. The mesh of water is set until computational limits of my RAM. I cleared the results in solver before running new calculation ('clear generated data') that it should not influence the solver run data afterwards. Is it possible that ansys searches from another folder the heat transfer file? May someone suggest CFX tutorial to investigate heat transfer problem independently?
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Old   August 9, 2016, 20:02
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It is NOT an error. It is a notice and is just making you aware of some issues around heat transfer coefficients.

Please post an image of your results and the geometry you are modelling. Also attach your output file and/or CCL.
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Old   August 10, 2016, 01:31
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Thanks for your reply!

I send the result, geometry and CCL file of water region temperature change as attachment: fluid inlet temperature 10 C and cladding temperature 50 C heating the water for low mass flow rate. I modelled the copper pipe as thin surface layer between fluid and cladding.


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File Type: png result.png (93.4 KB, 27 views)
Attached Files
File Type: zip Geometry.zip (17.8 KB, 6 views)
File Type: zip CCL file.zip (3.9 KB, 9 views)
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Old   August 10, 2016, 03:13
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The temperature is changing along the length of the pipe, so heat transfer is taking place. Can you explain what is wrong with the results?
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