Below is the plain C code for my heat flux UDF. I have no idea how to change this into something Fluent can use (I didn't write this code, I don't know any C!). The heat flux should be the same across the whole face at any given time and follow the equation Q=15E09*sin(t(pi/13E-09)).

Please could someone convert this into something useable by Fluent 6.1.1.8. It shouldn't take much time for someone who knows what they're doing. Thankyou.

#include <math.h>

double Q(double t) {

double A, PI, B, C;

unsigned int badReturn = -1;

A = pow(10., 9.);

PI = 3.14159265;

B = pow(10., -9.);

C = (15 * B);

if(t < 0 || t > C) return double(badReturn);

return A * sin(t*(PI/C)); }

The flux described by the C code you posted is:

Q = 15*10^9 sin(t*pi/(15*10^-9))

if t <= 15*10^-9

The function returns -1 if t < 0 (Never, time is never negative!) or if t > 15*10^-9.

I think you want to have the source only for t <= 15*10^-9, and no source after this time.

If so the code is the following:


#include "udf.h"

DEFINE_SOURCE(heat_source,c,t,dS,eqn)
{
real a,b,c,t, source;

/* Getting the current time in seconds */
t = CURRENT_TIME;

/* Calculating a, b and c */
a = pow(10., 9);
b = pow(10., -9);
c = 15.*b;

/* Calculating the source term */
if (t <= c)
{
source = a*sin(t*M_PI/c);
}
else
{
source = 0.;
}

dS[eqn] = 0.;
return source;
}


I hope it works.
Regards,
ap

Thankyou for your swift response. When I try to interpret the .c file which I copy/pasted the code into I get the following error:

cpp -IC:\fluent.inc\fluent6.1/src -IC:\fluent.inc\fluent6.1/cortex/src -IC:\fluent.inc\fluent6.1/client/src -IC:\fluent.inc\fluent6.1/multiport/src -I. -DUDFCONFIG_H="<udfconfig.h>" [.c file address]

Error: [.c file address]: line 1: parse error.

Any idea what could be causing this?

Sorry, I made a mistake in the definition of the DEFINE_SOURCE.

The following code is properly interpreted by FLUENT.


#include "udf.h"

DEFINE_SOURCE(heat_source,cell,thread,dS,eqn)

{

real a,b,c,t, source;



/* Getting the current time in seconds */

t = CURRENT_TIME;



/* Calculating a, b and c */

a = pow(10., 9);

b = pow(10., -9);

c = 15.*b;



/* Calculating the source term */

if (t <= c)

{

source = a*sin(t*M_PI/c);

}

else

{

source = 0.;

}



dS[eqn] = 0.;

return source;

}


Best regards,
ap

I still get the same error. Any other possibilities?

Can you e-mail me the file you're trying to compile?

Best regards, ap