a sinusoidal force added to the wall of combustion chamber
 

Hello, friends.
i would like to set up a sinusoidal force in top and bottom wall of the combustion chamber.
the geometry consists in two rectangle represent a burner and a combustion charmer. the force located on the wall will exicte wall oscillation.
the amplitude is 10e-7n/m3 and the frequency is 3838HZ.
i try source term for the momentum equation, it seems fail.
could anyone help me on this case?

the UDF code i written
 

DEFINE_SOURCE(oscillate, cell, ts, dS, eqn)
{
real source;
real time = CURRENT_TIME;
real x[ND_ND];
Thread *tm = THREAD_SUPER_THREAD(ts);
source = 0.00000001sin(3838*ime);
dS[eqn] = 0.08*6.28*2*3.1315926*cos(2*3.1315926*time);
return source;
}