[adi.ptb]

hello,I have a question that I hope someone can help me with,I want to study the effect of gravity in an inclined system that has a compressor at on of its ends,this must be done using dynamic layering,I wrote a udf for motion of compressor but my problem is that i dont know what should i add to my udf to account for inclined geometry since the moving boundary is not perpendicular to x or y axis and it has a 30 degree angle with respect to y axis,
any help would be appreciated,

udf:

DEFINE_CG_MOTION(piston,dt,vel,omega,time,dtime )
{
Thread *t;
real f=150.0;
real w=2.0*M_PI*f;
real xcomp=2.0e-3;
NV_S(vel,=,0.0);
NV_S(omega,=,0.0);
t = DT_THREAD(dt);
vel[]=xcomp*w*cos(w*time); this the part that i dont know what to use!!!!!!,0 is for motion in x direction and 1 for motion in y direction,
}

[adi.ptb]

hi,can I take my geometry to be horizontal and instead use -gcos30 and -gsin30 for gravitational acceleration in x and y directions or should I use the rotate option of fluent and rotate the system by 30 degrees and use -g in the y direction for acceleration,which one in correct?