Temporal array filter on moving airfoil

Hi everyone !

I try to understand how the temporal array filter works for a moving airfoil. I have an overset mesh with the airfoil and I want to use the temporal array filter to get the temporal derivative (substract timestep 2 - 1). The thing is that it is an up and down moving airfoil (sinusoidal motion) and I don’t understand how it is supposed to work between 2 timesteps. Paraview succeeded to do it but it’s weird because if the airfoil is moving then there is a part of the airfoil that should be filled with the other timestep right ? You can see on the pictures attached the operations I did and a contour where you can see timestep 2 in grey and timestep 1 in red.

Do you have any ideas ?