[Adnin]

Hi there,
I am a student currently preforming an fluent simulation and is in need of assistance. I am trying to simulate a pistons movement, however the cylinder has a curved shape thus eliminating the possibility of using the in-cylinder function. i have written a short udf cg-motion. i am not getting the wall(piston to move a long the cylinder surface. the udf is as follows:

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

DEFINE_CG_MOTION(piston, dt, vel, omega, time, dtime)
{
real pi = 3.141592;
real omega_constant = 50 * pi / 180;
omega[0] = - omega_constant;
}

The problem:
1. the wall(piston) is rotating along an axis(x-axis) on the wall itself, the rotation is correct(counter-clockwise). I just havent been able to move the axis of rotation away from the wall.

[Adnin]

this is the shape of the cylinder that i am working with.