[farhangraymand]

hi everyone,first time poster...
so im mdelling flow around a "stopping" rotating cylinder (motion with deceleration) and i need to obtain the angular velocity and torque exerted on the cylinder.ive written the following udf but fluent crashes everytime.does anyone know what the problem is and how to fix it?

[pakk]

There is no udf.

[farhangraymand]

#include "udf.h"
#include "mem.h"
#define PI 3.141592654
#define MU 0.01
real omega=5;
real deltat=0.2;
DEFINE_PROFILE(rotation,t,omega1)
{
real Tau_x=0;
real Tau_y=0;
real Tau=0;
real location[ND_ND];
real theta=0;
face_t f;
cell_t c;
real dudy1=0;
real dvdx1=0;
real T=0;
begin_f_loop(f,t)
{
theta=acos(location[0]/0.5);
if (location[1]<0)
{
theta=2*PI-theta;
}
F_C0(f,t);
dudy1=C_DUDY(c,t);
dvdx1=C_DVDX(c,t);
Tau_x=MU*dudy1;
Tau_y=MU*dvdx1;
Tau=Tau_x/cos(theta)-Tau_y/sin(theta);
T=T+Tau*PI*0.5;
}
end_f_loop(f,t)
omega1=omega1-T*deltat;
}

[AlexanderZ]

I think you forgot F_CENTROID macros.
Your location variable is not defined in your code, You may try this:

begin_f_loop(f,t)
{
F_CENTROID(location, f, t);
theta=acos(location[0]/0.5);
if (location[1]<0)
{
theta=2*PI-theta;
}

Best regards