deviation and Gradients
 

Hi,
In order to realize an equation (attached) I need to catch up some deviations (pressure Gradient and temperature Gradient).

- What is the best way to include deviations in a UDF? Should I use the Gradient Macro or is there a better way to use deviations?

- In my opinion I need a pointer on the deviations, are these pointer identic with the Macro-NAme (for examplecan I use C_P_G as pointer and function variable for the pressure deviation?)

- As a hint for me, Might this work? A= B*pressure'

.......
double A 0.0;
double B 0.0;

//variables

pressure' = C_P_G(c,t);

.......

Greetings,
Jim

I tried a small UDF (only to catch up the gradient of temperature und build an equation with it)

I think I have to add something or activate a hook in the solver system, but I don't get the problem fixed. Tried #include "mem.h", but this seems not to be the missing step.

Can someone please give my a feedback?


#include "udf.h"

DEFINE_PROPERTY(test_Gradienten,c,t)
{

/************************************************** **************************
Standard UDF Befehle
************************************************** ***************************/

double Rho = 0.0;
double gradient = 0.0;
double s1 = 5;

/************************************************** **************************
Variablen aufrufen
************************************************** ***************************/

gradient = C_T_G(c,t)[1];

/************************************************** *************************
Zeiger Druck und Temperatur
************************************************** ***************************/

Rho = 1 + gradient * s1;

return Rho;

}

C:\PROGRA~1\ANSYSI~1\v145\fluent\fluent14.5.0\win6 4\3ddp\fl1450s.exe 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.

Ensure that the pointer is not null. The macro might be invoked before the temperate gradient is calculated.

thank you. This one line fixed the UDF.