[majidroozbahani]

Hi all
I'm trying to learn and using dynamic mesh in ansys fluent but i get an error:
Update-Dynamic_mesh failed. Negative cell volume detected.
I read some articles about this error such as change the time steps and ... but my problem dosen't solve.
1. I use layering method with default setting.
2. The UDF that i use it:

DEFINE_CG_MOTION(trans, dt, vel, omega, time, dtime)
{
vel[1] = 0.9424*cos(9.424*time);
}

3. The mesh is quad--map and the cell length is 0.2

Can any one help me and tell me how should i set my Dynamic Mesh and its Zones?!
I would appreciate any kind of help