6DOF for flapping plate
 

I'm trying to model the flapping behavior of a flat plate in a tunnel in response to a pulsatile inflow. The flat plate is initially set at a 45 deg angle to the horizontal. I set up the 6DOF solver by 1) defining the plate's Ixx, Iyy, and mass in a UDF and 2) selecting 6DOF under dynamic mesh, selecting the plate zone, and inputting the center of gravity location.

However, instead of getting a rotating plate in response to the sinusoidal flow, the plate only shifts horizontally and I get a warning message in the main window saying there is no angular acceleration.

Any ideas on how to correct the problem?