UDF Using New Coordinates Instead of Original
 

Hi All,

Below is my UDF that I have been working on for rotating the points of an airfoil. This code works in my previous application where I calculated a new Y value based on X, but now I just want to read the x and y coordinates, rotate them, then output the rotated coordinates. This code works but it is calculated each time step based on the previously rotated points instead of the original baseline coordinates thus creating too much rotation of the coordinates. Can anyone help so that it always reads the original x and y coordinates?

Thanks,

Thomas

#include "udf.h"
#define FTT 0.4
#define chord 1.00000
/*upper surface*/
DEFINE_GRID_MOTION(Up, domain, dt, time, dtime)
{
Thread *tf = DT_THREAD (dt);
face_t f;
Node *node_p;

real x,y,theta,x_s,y_s,T_max,Tmorph,freq,omega,xuc,yuc, Rux,Ruy,rcux,rcuy;
int n;
freq = 0.2;
omega = 2 * M_PI * freq;
Tmorph= 0.0555555794;
T_max = FTT+Tmorph;
x_s = 0.25*chord;
y_s = 0;

SET_DEFORMING_THREAD_FLAG (THREAD_T0 (tf));

begin_f_loop (f, tf)
{
f_node_loop (f, tf, n)
{
node_p = F_NODE(f, tf, n);
x = NODE_X(node_p);
y = NODE_Y(node_p);

if (NODE_POS_NEED_UPDATE (node_p))
{

NODE_POS_UPDATED (node_p);


if ( x < x_s) {

if ( CURRENT_TIME >= FTT && CURRENT_TIME <= T_max) {

theta = omega * (CURRENT_TIME - FTT);
xuc = x - x_s;
yuc = y - y_s;
Rux = ((xuc * cos(-theta)) + (yuc * sin(-theta)));
Ruy = ((xuc * -sin(-theta)) + (yuc * cos(-theta)));
rcux = Rux + x_s;
rcuy = Ruy + y_s;
NODE_Y (node_p) = rcuy ;

}
/*morphing stops*/
if ( CURRENT_TIME > T_max) {
theta = omega * Tmorph;
xuc = x - x_s;
yuc = y - y_s;
Rux = ((xuc * cos(-theta)) + (yuc * sin(-theta)));
Ruy = ((xuc * -sin(-theta)) + (yuc * cos(-theta)));
rcux = Rux + x_s;
rcuy = Ruy + y_s;
NODE_Y (node_p) = rcuy;

}
}
}
end_f_loop (f, tf);
}
}
}