[SanchoBuendia]

Hi everyone,

I would like to simulate the flow in pipe using the axisymmetry in order to do this I created on rectangle and apply the axisymmetry, but I need to get the radius of the pipe or the coordinate y of the each cell because my source term is a force that depend of distance between the cell and axis and I want to do it to all cell in each iterate. I put for write the coordinate and the source term in the screen and it seems that the uff to remain in loop to only cell. How do I fix this?

DEFINE_SOURCE(electroosmotic,cell,thread,dS,eqn)
{
double source;
double Ir;
double IR;
double k;
double y;

FILE *saida;

real xc[ND_ND];
begin_c_loop_all(cell, thread)
{

C_CENTROID(xc,cell,thread);


y = xc[1];

k = (1/pow(((ee*Kb*T)/(2*NA*pow(el,2)*ninf)),0.5));

Ir = 1 + pow((k*y)/2,2) + pow((k*y)/2,4)/4 + pow((k*y)/2,6)/24 + pow((k*y)/2,8)/(24*24) + pow((k*y)/2,10)/(120*120);

IR = 1 + pow((k*R1)/2,2) + pow((k*R1)/2,4)/4 + pow((k*R1)/2,6)/24 + pow((k*R1)/2,8)/(24*24) + pow((k*R1)/2,10)/(120*120);

source = -ee*U0*pow(k,2)*Ex*(Ir/IR);

saida = fopen("saidaR.txt","a");
fprintf(saida,"%g %g\n", y, source);
fclose(saida);

dS[eqn] = 0.0;
return source;
}
end_c_loop_all(cell, thread)

}

[obscureed]

Hi SanchoBuendia,

Quoting from the ANSYS Fluent Customization Manual:
Your UDF will need to compute the real source term only for a single cell and return the value to the solver

So you don't need a cell loop at all. (And anyway, if you did, it would be a bad idea to open a file, write a line, and close the file on every iteration of a cell loop. And any fopen/fprintf/fclose commands are incompatible with parallel. You could consider Message("y=%g source=%g\n",y,source); to send output to the Fluent command window.)

Please look at the manual and try to adapt the examples. Good luck!

Ed

[sumagaji]

Hi everyone,
I am working on parabolic trough receiver and have heat flux data from ray tracing model (the set of data is as shown below. I want to hook the data to Ansys Fluent tool using UDF as wall boundary condition. in trying to do so, the following codes were used. But whenever i interpret the second code it display parse error line 1. please can someone help me out?

#include ''udf.h''
#include ''sg. h''
DEFINE_ON_DEMAND(copy_uds_to_udm)
{
Domain*d=Get_Domain(1);
Thread*t;
cell_t c;
thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
c_UDMI(c,t,0) =c_UDSI(c,t,0);
}
end_c_loop(c,t)
}
return;
}



Second codes

DEFINE_SOURCE( solar_heat, c,t,ds,eqn)
{
real source;
ds[eqn] =0.0;
source =C_UDMI(c,t,0);
return source;
}


The data set sample is:
circumferencial angle heat flux (w/m2)
-90 987
-80 784
-70 654
-60 453
-50 441
-40 342
-30 231
-20 212
-10 187
0 143
10 121
20 78
.
.
.
90 0

Thank you for given me the opportunity to share my problem. hope to have your kind assistance.

[obscureed]

Hi Sumagaji

(Why isn't this a separate thread, by the way?)

Are these two separate files? If so, you need #include ''udf.h'' at the start of each. Or, if you prefer, put both into one file.

Good luck!
Ed

[sumagaji]

Thank you for the responses but actually sir, i used them as two separate thread and i put #include"udf.h" as header and got same error