Are these reverse von karman vortex street?
 

Hi,

I'm trying to analyze the vorticity plot I got from my simulation.

Are these pics indicative of reverse von karman vortex street? ie thrust producing? I'm not too sure.

They are from the simulation of oscillating airfoils.

Thanks in advance

Its too hard to say from your present figure. One thing that you would want to do is to add tracer particles and that would clearly show Reverse Von Karman street. What kind of motion is this and what are the motion parameters like amplitude and reduced frequency? A simple way to check if thrust is produced is to have a look at the wall normal velocity profile 5 chords downstream. If the net average is positive you have thrust production.