Learning Forum

[Jancos]

Hi all,

Can anyone help me with this UDF. After I interpreted my UDF , set UDMs on 4 and put new momentum source I initializate my calculation but when I am checking counturs the values of my UDMs are 0. And when I start calculation my Fluent crashed. 

THIS MY UDF:

 

[DrAmine]

We will provide guidance only. Paste the lines here.

[Jancos]

#include "udf.h"

 

#define N 94208

#define xm -8.86E-9

#define ro 997.96

#define beta 21.37E-5

#define To 298.5

#define mi 12.566E-7

#define vf 3.28E-5

 

 

float GradB[N] =

{...};// my values number of elements 94208

 

DEFINE_SOURCE(xmagnetic_source,c,t,dS,eqn)

{

real xm_source;

real Temp;

Domain *d;

int i;

i = 0;

 

thread_loop_c(t,d)// loop over all cells in model

{

begin_c_loop(c,t)

{

Temp = C_T(c,t);

xm_source=(-((xm*ro*beta*(Temp-To)*GradB*vf)/(2*mi)));

C_UDMI(c,t,0) = GradB;

C_UDMI(c,t,1) = xm_source;

i++;

}

end_c_loop(c,t)

}

return xm_source;

}

DEFINE_SOURCE(ymagnetic_source,c,t,dS,eqn)

{

real ym_source;

real Temp;

Domain *d;

int i;

i = 0;

 

thread_loop_c(t,d)// loop over all cells in model

{

begin_c_loop(c,t)

{

Temp = C_T(c,t);

ym_source=(-((xm*ro*beta*(Temp-To)*GradB*vf)/(2*mi)));

C_UDMI(c,t,2) = ym_source;

i++;

}

end_c_loop(c,t)

}

return ym_source;

}

DEFINE_SOURCE(zmagnetic_source,c,t,dS,eqn)

{

real zm_source;

real Temp;

Domain *d;

int i;

i = 0;

 

thread_loop_c(t,d)// loop over all cells in model

{

begin_c_loop(c,t)

{

Temp = C_T(c,t);

zm_source=(-((xm*ro*beta*(Temp-To)*GradB*vf)/(2*mi)));

C_UDMI(c,t,3) = zm_source;

i++;

}

end_c_loop(c,t)

}

return zm_source;

}

[DrAmine]

Actually there is no need to do a loop inside of a define source udf. Check the manual for more details and attend a training if possible. Gradb is declares but not defined. You require a loop if the counter i if you need to use values from the array.

[Jancos]

In my array i have values which represent gradient of magnetic field in every cell center, so I need to have it . And my loop in define source calculate in every cell value of magnetic buoyacy force. Do you have any idea how write this UDF?

 

[DrAmine]

Check the manual and standard C manuals.