[cjc021206]

I use UDF to calculate the moment on a fan. The UDF is


#include "udf.h"
#include "mem.h"
#include "dynamesh_tools.h"

#define INERTIA 1.7

static real alpha_z0=0.0, omega_z0=0.0, theta_z0=0.0;

int damp_f( real theta, real alpha, real* vol, real* r_m ){
real x0=-300, y0=137.5, x1=-80, y1=-600;
real x0r, y0r, dx, dy, d01, ddf;
x0r = x0 * cos( theta ) - y0 * sin( theta );
y0r = x0 * sin( theta ) + y0 * cos( theta );
dx = x0r - x1;
dy = y0r - y1;
d01 = sqrt( pow(dx, 2) + pow(dy, 2) );
*vol = d01 * alpha;
*r_m = fabs( (y1 * x0r - x1 * y0r) / d01 );
return 0;
}

DEFINE_CG_MOTION( piston_damp_sp0, dt, vel, omega, time, dtime )
{

face_t f;
cell_t c;
real f_glob[3], m_glob[3], domega_z, x_cg[ND_ND], m_damp, v_damp;
int i, status;

NV_S(omega, =, 0.0);

for(i=0;i<=3;i++)
{
f_glob=0;
m_glob=0;
}

x_cg[0] = 0;
x_cg[1] = 0;

Domain *domain= Get_Domain (1);
Thread *tf1 = Lookup_Thread (domain, 3);
Compute_Force_And_Moment (domain, tf1, x_cg, f_glob, m_glob, TRUE);

real* vol;
real* r_m;
status = damp_f( theta_z0, alpha_z0, vol, r_m );
v_damp = 4 * (*vol) * (*r_m) ;

m_damp = 0;
alpha_z0 = (m_glob[2] - m_damp - v_damp )/INERTIA;
domega_z = dtime * alpha_z0;
omega_z0 += domega_z;
theta_z0 = DT_THETA(dt)[2];

Message ("ntime=%f, tz=%.10lf, oz1=%.10lf, oz2=%.10lf, force_x=%.1f ,force_y=%.1f, moment_z=%f, vol=%.1f, rm=%.1f ", \
time, DT_THETA(dt)[2], DT_OMEGA_CG(dt)[2], theta_z0, f_glob[0], f_glob[1], m_glob[2], *vol, *r_m );

omega[2]=omega_z0;

}



I run the calculation with 2 cores in parallel mode，and get the error the the fluent is auto-closed.



Node 0: Process 5204: Received signal SIGSEGV.

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Node 1: Process 9392: Received signal SIGSEGV.

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MPI Application rank 0 exited before MPI_Finalize() with status 2



I can solve this problem with putting the calculations those in function damp_f into DEFINE_CG_MOTION. However, I wonder if a function can be called in UDF and how to call a function? Thx

[AlexanderZ]

you can call functions in UDF same way as in C language
actually, what you've done seems to be correct