[wpdeng]

1, When I compiled my UDFs, it didn't show any error. But after initialized Fluent, an error occurs.

2, Error: received a fatal signal (segmentation fault).


3, /*My UDF is about the fluid properties depending on temperatures.*/
/* my_density */
#include "udf.h"
double Tm1[2] = {
293.15 ,
294.15
};

double D[2] = {
0.16632 ,
0.03831
};
DEFINE_PROPERTY(my_density,c,t)
{
int i;
double density;
double temp = C_T(c,t);
if(temp <= Tm1[0]) density = D[0];
else if(temp > Tm1[1]) density = D[1];
else
{
for(i = 0;i <1;i++)
{
if(temp > Tm1[i] && temp <= Tm1[i+1])
density = D[i] + (temp - Tm1[i]) * (D[i+1] - D[i]) / (Tm1[i+1] - Tm1[i]);
}
}
return density;
}

4, Help me, Please! I really want to solve this problem quickly.

[pakk]

First initialize, then load the UDF.

[wpdeng]

Originally Posted by pakk

First initialize, then load the UDF.

My UDF is the properties of the fluid.
If initialize first, how to define the properties?

[pakk]

That does not really matter, but if possible do something close to your expected result. Define it for example with a uniform density based on a typical temperature in your problem.

[wpdeng]

Originally Posted by pakk

That does not really matter, but if possible do something close to your expected result. Define it for example with a uniform density based on a typical temperature in your problem.

Really really thank you! I tried the method you told, the fluent can running!

[kar1209]

I am getting the "received a fatal signal (segmentation fault)" error. Is it because the function is not able to access the previous timestep values using F_U_M1 and C_U_M1?

#include"udf.h"
DEFINE_PROFILE(CBC_u_vel,t,i)
{
real u_f_old, u_c_old, u_temp, u_cor, mass_out = 0, ds;
real x[ND_ND], y[ND_ND];
Thread *nt;
face_t f;
cell_t c, nc;
begin_f_loop(f,t)
{
mass_out+=F_FLUX(f,t);
}
end_f_loop(f,t)
u_cor = (20 - mass_out)/20;
begin_f_loop(f,t)
{
nc = F_C0(f,t);
nt = THREAD_T0(t);
F_CENTROID(x,f,t);
C_CENTROID(y,nc,nt);
ds = x[0] - y[0];
u_f_old = F_U_M1(f,t);
u_c_old = C_U_M1(nc,nt);
u_temp = u_f_old - CURRENT_TIMESTEP*(u_f_old - u_c_old)/ds;
F_PROFILE(f,t,i) = u_temp + u_cor;
}
end_f_loop(f,t)
}

The UDF manual says:

Note that data from C_T_M1 is available only if user-defined scalars are defined.

How do I define and use user-defined scalars to access data using C_U_M1 in my program?

Any help would be appreciated.

[wpdeng]

Originally Posted by kar1209

I am getting the "received a fatal signal (segmentation fault)" error. Is it because the function is not able to access the previous timestep values using F_U_M1 and C_U_M1?

#include"udf.h"
DEFINE_PROFILE(CBC_u_vel,t,i)
{
real u_f_old, u_c_old, u_temp, u_cor, mass_out = 0, ds;
real x[ND_ND], y[ND_ND];
Thread *nt;
face_t f;
cell_t c, nc;
begin_f_loop(f,t)
{
mass_out+=F_FLUX(f,t);
}
end_f_loop(f,t)
u_cor = (20 - mass_out)/20;
begin_f_loop(f,t)
{
nc = F_C0(f,t);
nt = THREAD_T0(t);
F_CENTROID(x,f,t);
C_CENTROID(y,nc,nt);
ds = x[0] - y[0];
u_f_old = F_U_M1(f,t);
u_c_old = C_U_M1(nc,nt);
u_temp = u_f_old - CURRENT_TIMESTEP*(u_f_old - u_c_old)/ds;
F_PROFILE(f,t,i) = u_temp + u_cor;
}
end_f_loop(f,t)
}

The UDF manual says:


How do I define and use user-defined scalars to access data using C_U_M1 in my program?

Any help would be appreciated.

I don't know your UDFs, maybe you can check carefully by yourself.

But if you cannot running the Fluent, you can try the method, which using a constant velocity to initialize the Fluent and then load your UDFs to running the Fluent.

Maybe your problems can be solved. If cannot, you can ask for help to others.