CFD Online Discussion Forums - User defined viscosity

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Far	August 15, 2015 13:20

User defined viscosity - error in load

1 Attachment(s)

Here is my udf for defining the viscosity as function of temperature and pressure:

Code:

#include "udf.h"



DEFINE_PROPERTY(viscosity,c,t)

{

real mu_laminar, temp, pr; 



temp = C_T(c,t);



pr = C_T(c,t); 



mu_laminar = 0.0127*exp(0.000000213345*(pr-

101345))*exp(0.029*(temp-293));



return mu_laminar;



}

After compilation i get following message, which i am sure is OK!

D:\a\libudf\win64\3ddp\libudf.dll
Copied D:\a/D:\a\viscosity .c to libudf\src
udf_names.c and user_nt.udf files in 3ddp are upto date.
(system "copy "C:\PROGRA~1\ANSYSI~1\v160\fluent"\fluent16.0.0\sr c\udf\makefile_nt.udf "libudf\win64\3ddp\makefile" ")
1 file(s) copied.
(chdir "libudf")(chdir "win64\3ddp")
Done.

Then I click on load option to make it available to solver, but then I get this error message :

http://www.cfd-online.com/Forums/att...1&d=1439659112

Any suggestion?

Far	August 16, 2015 01:26

3 Attachment(s)

Today morning, just started the procedure again without any changes to system configuration or Fluent settings and surprisingly every thing is working fine.

Though you can see that I have made few changes to UDF but that is not more than adding comments etc...

Here is the message I received now (perfectly working udf )

http://www.cfd-online.com/Forums/att...1&d=1439702414

And UDF (also attached)

http://www.cfd-online.com/Forums/att...1&d=1439702177

PS: I am using Visual studio Express 12.0. For editing of udf files ( c files in fact), I am using notepad++.

`e`	August 18, 2015 06:38

I generally find it safest to first unload the compiled library before building and loading a new library (instructions). Restarting Fluent would have a similar effect which could explain why the compilation worked next day.

Far	August 18, 2015 19:39

Just wondering, what is the purpose of return command?

`e`	August 18, 2015 20:00

Fluent UDF macros are implemented with the usual C function definitions which may return a value. Article on C Functions. In this particular case, the DEFINE_PROPERTY macro is called for each cell and returns the viscosity value. This process occurs when the properties are updated (near the end of each iteration before the convergence check).

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