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-   -   specific heat capacity changing with temperature (http://www.cfd-online.com/Forums/cfx/104667-specific-heat-capacity-changing-temperature.html)

a_cucen July 12, 2012 11:41

specific heat capacity changing with temperature
 
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.

Danial Q July 12, 2012 18:02

HI
 
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

a_cucen July 12, 2012 19:29

I defined Cp as a function of temperature. I imported a table that shows Cp changes with temperature.

Danial Q July 12, 2012 23:31

HI
 
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.

a_cucen July 13, 2012 04:37

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

Danial Q July 13, 2012 20:21

HI
 
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.

Cheers

a_cucen July 14, 2012 05:03

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.

cfdgremlin July 16, 2012 12:25

Dear Ahmet,

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

CG

a_cucen July 17, 2012 02:12

dear cfdgremlin,

I couldn' t define cp from table values but I' m using Nasa Polynomials now.

Saima December 12, 2012 17:25

Could you pls tell me how you implemented polynomial for specific heat capacity in CFX pre?

antara October 6, 2015 18:15

Quote:

Originally Posted by a_cucen (Post 371783)
dear cfdgremlin,

I couldn' t define cp from table values but I' m using Nasa Polynomials now.

How do you get Nasa Polynomials? Can you please explain it? I'll have to use Real gas property for supercritical simulation.

Antanas October 7, 2015 01:24

Quote:

Originally Posted by antara (Post 566871)
How do you get Nasa Polynomials? Can you please explain it? I'll have to use Real gas property for supercritical simulation.

Material Props -> Specific Heat Capacity Option = NASA format

antara October 7, 2015 11:36

Quote:

Originally Posted by Antanas (Post 566896)
Material Props -> Specific Heat Capacity Option = NASA format

Which CFD code are you using for your case? I'm using ANSYS Fluent. I couldn't find the NASA format on Specific Heat Capacity Option under material props option.

Opaque October 7, 2015 11:44

You are asking in the wrong forum

Antanas October 8, 2015 00:13

Quote:

Originally Posted by antara (Post 567007)
Which CFD code are you using for your case? I'm using ANSYS Fluent. I couldn't find the NASA format on Specific Heat Capacity Option under material props option.

This is CFX forum, so my post concerns CFX.


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