raddi translating deformable cylinder UDF
 

hi every one

i wan simulate a raddi deformable cylinder with plunging motion i use this UDF for radial deformation

DEFINE_GRID_MOTION(RADII, domain, dt, time, dtime)
{

Thread *tf = DT_THREAD (dt);
face_t f;
Node *v;
real x_coor;
real x_centre=0;
real y_coor;
real rayon;
real freq = 3.183;
real alpha;
real temps;
real R =0.25;
int n;
// FILE *fp = fopen(UDF_FILENAME, "r");

/* set deforming flag on adjacent cell zone */
SET_DEFORMING_THREAD_FLAG (THREAD_T0 (tf));



//temps = RP_Get_Real("flow-time");
temps = time+dtime;
begin_f_loop (f, tf)
{
f_node_loop (f, tf, n)
{
v = F_NODE (f, tf, n);
if (NODE_POS_NEED_UPDATE (v))
{
NODE_POS_UPDATED (v);

x_coor= NODE_X (v);
y_coor= NODE_Y (v);
alpha = 0.125;

NODE_X (v) = x_coor- x_coor*(alpha*cos(2*M_PI*4*freq*temps));
NODE_Y (v) = y_coor- y_coor*(alpha*cos(2*M_PI*4*freq*temps));

}

}
}
end_f_loop (f, tf);
}


for plunging motion i use zone motion udf

DEFINE_ZONE_MOTION(motion_TRANS,omega,axis,origin, velocity,time,dtime)
{


/************************************************** ***/
real corde = 0.1;
// real freq = 0.224;
real freq = 4;
real ho = 1;
real ao = 0.84811*(M_PI/2); /*76.33°*/
real phy = M_PI/2;


/************************************************** ***/

//if (time > (1/(4*freq)))
//{

velocity[1] = (ho*corde*cos(2*M_PI*freq*(time+dtime)) - ho*corde*cos(2*M_PI*freq*time))/dtime;


// origin[0] =0.0;
// origin[1] = ho*corde*cos(2*M_PI*freq*(time+dtime));
//}
return;
}


after simulation i generate animation file in TECPLOT

i found Unphysical results



my question is : are the combination between ZONE MOTION and GRID MOTION udfs appropriate for combined deflection translation motions or not



please any help will be very appreciated