dynamic mesh setup
 

Hi guys.
I am trying to generate 2D sinusoidal waves in fluent with the help of a oscillating wall (dynamic mesh). I have written the udf and it works fine.
But when i run the calculation, after about 50 time steps, it shows error like pressure correction, velocity field diverging etc.

I am using a rectangular mesh. I have tried both iterative and non iterative solutions. I have attached a picture of my mesh around the moving wall. The vertical wall on the left in the picture is the moving wall. Can anybody please explain why the errors are occurring.

Also how is the amplitude of the waves generated related to the amplitude of the moving wall. I want to generate short wavelength and short period waves. What equation of motion of the wall should i use.

Thanks for your time.