CFD Online Discussion Forums - Alternate way to model Flapping Wings

I have simulated flow over sinusoidally oscillating flatplate using DEFINE_CG_MOTION in fluent.I used rigid body boundary condition for FlatPlate and Fluid Inner and their motion is defined by the UDF.
But this method makes the fluid (FluidInner) also to oscillate which is not the actual case(Ideally, the plate is supposed to oscillate in a stationary/steady freestream fluid).

I would like to oscillate the quad mesh and the flat plate as a whole but does not want to impart any motion to the fluid (Fluid Inner).

Is there any way to do it? Please help.

Additional details:

Quote:

#include "udf.h"
#define FREQUENCY 60

static real velMax = -3.0;

DEFINE_CG_MOTION(plate_oscil_udf, dt, cg_vel, cg_omega, time, dtime)
{
real * position;
NV_S(cg_vel,=,0);
NV_S(cg_omega,=,0);
cg_vel[1] = velMax*cos(2*3.1415*FREQUENCY*time);

position = DT_CG(dt);
Message("\n\n Y co-ordinate:%f velocity:%f delt:%f\n",position[1],cg_vel[1],dtime);

}