Calculating pitching moment for power input

Zonexo

Hi,

I need to calculate the pitching moment of a flapping airfoil in order to obtain the power input. In order to get the moment, I usually multiply the force on the airfoil surface by the distance to the pitching axis at each grid location and sum them up.

However, in some simulations, this was not done and I'm now left with the total lift and drag value,together with the flapping configuration. Is there anyway I can still get the moment? I don't need it to be exact, just an approximation will do. I believe I need to know the center of pressure but it is changing all the time since the force is varying ...

Hope someone can help. Thanks