Wave tank dynamic mesh
 

Hi!
This is my first post in this forum and first of all I apologize for my bad English. I hope you understand me anyway:)
I want to simulate a numerical wave tank with dynamic mesh. First, I have simulates a piston type wave maker, as in the tutorial 10 (Simulation of Wave Generation in a tank). This simulation works. The Wave Maker oscillates in both directions of the starting position.
Now I want to simulate a flap-type wave maker. I've changed my UDF so that I generate a rotation around the z-axis. The rotation is also generated, but only in one direction. For better understanding I made a sketch. I want to have the motion in Figure 2.
I hope someone can help me.
The very simple udf:

#include "udf.h"
#define pi 3.14159265
#define g 9.81 //Schwerkraft
#define a 0.05 //Wellenamplitude
#define h 1 //Wassertiefe
#define L 2 //Wellenlänge
DEFINE_CG_MOTION(wave, dt, vel, omega, time, dtime)
{
real k,w,S;
S=0.07254;
k=2*pi/L;
w=sqrt(k*g*tanh(k*h));
omega[2]=(S/2)*w*cos(w*time);
}

Regards,
Doro