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Old   March 6, 2011, 14:22
Default CG_motion problem
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I have to simulate a cylinder contrained with a spring and loaded only with its weight. I've written this UDF but monitoring the X-position of the center of the body it tends to 1mm and Cd tends to 0 .... where are the mistakes?

Thanks a lot for your help

#include "udf.h"

DEFINE_CG_MOTION(oscillazione,dt,vel,omega,time,dt ime)

real x[ND_ND];
Thread *t;
face_t f;
real A[ND_ND];
real Ft,F_el,F_pressure, dv, v_prev;
real Keq= 50.0;
real m = 0.25;

NV_S(vel, =, 0.0);

t = DT_THREAD(dt);

F_pressure = 0.0;

F_el += -Keq*x[0]; /* is this wrong? */
F_pressure += F_P(f,t) * A[0]; /* or F_P*NV_MAG(A) ? */

dv = dtime * (Ft / m);

v_prev += dv;

vel[0] = v_prev;
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