[crevoise]

Hello

I am writting an UDF in order to define the viscosity of my fluid

#include "udf.h" 
real visc;

DEFINE_PROPERTY(gas_viscosity,c,t)
{
        real temp = C_T(c,t);
	visc = function of temp;
	return visc;
}

This is properly working when I am interpreting the UDF.

However, when I am compiling the UDF, I am getting, while doing the initialization, the followin error:

Error: 
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: #f

I have put some pointer, and found out that C_T(c,t) is returning 0.
So that's might explain the error message.

The questions are:
1/ Why C_T(c,t) is giving 0?
2/ Why while interpreting, this is working?

Does anyone has some idea about this problem?
I've seen a similar post on the forum, but without answer on how to solve this.
http://www.cfd-online.com/Forums/flu...violation.html

Thanks for any help

[blackmask]

#include "udf.h" 
real visc;

DEFINE_PROPERTY(gas_viscosity,c,t)
{
        real temp = NNULLP(THREAD_STORAGE(t, SV_T)) ? C_T(c,t) : 300 ;
    visc = function of temp;
    return visc;
}

[pakk]

One more remark, that has nothing to do with your current problem, but might otherwise cause problems later on: define your variables local, not global:

#include "udf.h" 

DEFINE_PROPERTY(gas_viscosity,c,t)
{
    real visc;
    real temp = NNULLP(THREAD_STORAGE(t, SV_T)) ? C_T(c,t) : 300 ;
    visc = function of temp;
    return visc;
}

The difference is where you define "real visc".

[crevoise]

Thank you a lot for your answers.
I came to solve my problem, which was I was not compiling my udf with the proper header... a bit silly mistake

Thanks again anyway

[pakk]

It is good that you solved the problem.
But now I am curious: what was the wrong header that you used?
Here, you show that you used #include "udf.h", which is I think what it should be. Or are you referring to a different kind of header?

I ask it because your answer might help somebody else in the future who has the same problem.

[crevoise]

Hello Pakk

I was referring to another kind of header. (Maybe I am not using the proper terminology)
While compiling, you have to refer to the proper library 'fl1400.lib'

At first, my compilation was referring to the library found in the folder
'../fluent14.0.0/win64/3ddp' while I was not in a double precision
When I pointed the '../fluent14.0.0/win64/3d' , everything work well.

I don't know if it sounds clear, if not just ask and I'll try to be more precise.

[pakk]

I think I understand what you mean now. I think you add it in the box called 'header file', but I could be wrong about that.

One thing: in the 'Compiled UDFs' box I never use anything in the 'Header Files' box, I only add 'Source Files'. And udfs compile without problem. (And I would expect that the files you add in 'Header Files' should end in ".h", not in ".lib".)

I would think that in a proper installation, Fluent should find the file 'fl1400.lib' automatically. It might mean that some setting in your computer is not what it should be.

If it is not a problem for you that you have to add this filename manually every time, it is of course ok.