Originally Posted by abhinavgupta88 (Post 377396)

I have a 2D Geometry which has Piston on two sides and Top and Bottom are walls. I wanna move the Two Pistons Simultaneously using the UDF. For motion I am using Sine Function. I am using Fluent. Please Help

Originally Posted by abhinavgupta88 (Post 378219)

I have gone through the Manual. I am able to compile my UDF and Hook it to the walls. But I can see both the walls moving in the same direction. I am using the following UDF:
#include "udf.h"
#include "dynamesh_tools.h"

/************************************************** ********************/
/***** UDF for displacer motiion *****/
/************************************************** ********************/

DEFINE_CG_MOTION(displacer_func, dt, vel, omega, time, dtime)

{



Thread *t;
face_t f;
real a = 1.58712757;
real pai = 3.141592654;

/* reset velocities */
NV_S (vel, =, 0.0);
NV_S (omega, =, 0.0);

if (!Data_Valid_P ())
return;

t=DT_THREAD (dt);

if(time<=8.0)



vel[0] = ( a * ( cos(2*pai*75*time)) ) ;
else


vel[0] = -( a * ( cos(2*pai*75*time)) ) ;


}

I appreciate if anyone can help.

Originally Posted by syavash (Post 378226)

well, you should make two further steps.
1.separate two pistons in two distinct zones (if not already.)
2.make a copy of your define cg motion with a different name and a minus sign in velocity. Now assign each cg motion into one of pistons.
Good luck.

Originally Posted by abhinavgupta88 (Post 378227)

Thank You for the Reply. You mean to say Separate Two pistons in two distinct zones, in Gambit. I understand what you wrote but I am little confused with first step.