flapping wing UDF code
 

I'm simulating a flapping wing.

The UDF code is as follows:

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

real w, pi, Aroll, Apitch, roll, droll, pitch, dpitch, yaw, dyaw, frequency, T;
real Ar, Ap, Ay;

DEFINE_CG_MOTION(code, dt, v_cg, omega, time, dtime)

{
Thread *t;

NV_S(v_cg, =, 0.0);
NV_S(omega, =, 0.0);

if (!Data_Valid_P())
{
Message("Wrong\n");
return;
}

t=DT_THREAD((Dynamic_Thread*)dt);

frequency = 3.0;

pi = 3.141592654;

/* define motion variables */

Ar = 30.0; /*roll amplitude*/
Ap = 5.0; /*pitch amplitude*/
Ay = 0.0; /*yaw amplitude*/

Aroll = Ar*pi/180.0; /*conversion to radians*/
Apitch = Ap*pi/180.0; /*conversion to radians*/

w=2.0*pi*frequency; /*omega (radians)*/
T=1.0/frequency;

roll = Aroll*sin(w*time + pi/2);
droll = w*Aroll*cos(w*time + pi/2);

pitch = Apitch*sin(w*time+pi/2);
dpitch = w*Apitch*cos(w*time+pi/2);

/*euler angles initial frame mod 1*/

omega[0] = droll;
omega[1] = 0;
omega[2] = 0;

Message("time:%f omegax:%f omegay:%f omegaz:%f \n", time, omega[0], omega[1],omega[2]);

}

I need to consider pitch and roll rotation simultaneously. However, when I add pitch rotation to the code the wing movement becomes wrong.

Any idea what I should do about this?

Is that because of using sinusoid function for pitch rotation or incorrect code?