ItÔÇÖs center (x,y)=(0,0)
Here is fluent settings.
Following figure describes the concept of unsteady aerodynamic force.
The theodorsen function says when U/Bf(Non-dimensional wind speed)=0, both LyR and LyI =0 , which means no lift force when U=0(m/sec).But actually, lift force work on oscillating flat plate in no wind by my analysis model.