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specific heat capacity changing with temperature

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Old   July 12, 2012, 11:41
Default specific heat capacity changing with temperature
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Ahmet
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Dear all,

I have a case that specific hat capacity changes with temperature. After solver manager starts , I get this failure. What can I do to solve this problem?

+--------------------------------------------------------------------+
| Initial Conditions Supplied by Fields in the Input Files |
+--------------------------------------------------------------------+

Domain Name : ICEngine
Mesh Coordinates

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Specific heat information for fluid component "C7H16l" is either |
| missing or invalid. Supported formats are: NASA polynomials, Zero |
| pressure polynomials or constant values for the specific heat. |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| Writing crash recovery file |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine SU_PROP |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX solver exited with return code 1. No results file |
| has been created. |
+--------------------------------------------------------------------+

End of solution stage.
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Old   July 12, 2012, 18:02
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How did you define your Cp as function of time, I mean which format?Because ERROR clearly describes the allowable formats, you can use. If you have specified as expression then post it here.

Thanks
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Old   July 12, 2012, 19:29
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I defined Cp as a function of temperature. I imported a table that shows Cp changes with temperature.
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Old   July 12, 2012, 23:31
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Then this error clearly states that your table has some problem (i.e format/coding error) because solver is unable to read it. Without looking at your table, i cant be sure about anything. But you may use Polynomials format by developing an equation or writing a CEL Expression. Have you selected the real gas (EOS) option for your material because I guess table format is supported only for real gas problems. These all are possibilities, i can think of right now.

Last edited by Danial Q; July 13, 2012 at 00:00.
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Old   July 13, 2012, 04:37
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Here is an example of my table. I have imported this table and if my values are out of the table, it must be extrapolate. Is there something wrong about my table?

Temperature (K) Cp (J/g*K)
186,72 1,9651
188,81 1,9673
190,9 1,9695
192,99 1,9718
195,07 1,9743
197,16 1,9768
199,25 1,9794
201,34 1,9821
203,42 1,985
205,51 1,9879
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Old   July 13, 2012, 20:21
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I already told you that (.rgp) format table is used to define some real gas properties of user material. So, you can add that table by choosing material properties option to table and filling component and file name. Else, you can just use ZERO pressure POLYNOMIAL if your Cp and Enthalpy of materials are only function of temps. In my opinion, it would suit you the best.
For more details you can just read ansys cfd solver theory guide and tutorials.

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Old   July 14, 2012, 05:03
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Dear Danial, I have found that information that If I want to choose heat capacity changing with temperature, I have to use Nasa polynomials. So I' m trying to use Nasa polynomials. Thank you for your help.
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Old   July 16, 2012, 12:25
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Dear Ahmet,

is the Cp you are trying to define being applied to a particle phase, by any chance?

CG
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Old   July 17, 2012, 02:12
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dear cfdgremlin,

I couldn' t define cp from table values but I' m using Nasa Polynomials now.
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Old   December 12, 2012, 17:25
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Could you pls tell me how you implemented polynomial for specific heat capacity in CFX pre?
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