The graphics below show the structure of the free wake behind an oscillating airfoil. The case has been computed with an unsteady vorticity formulation of the boundary element method.
Impulsive Start of Elliptic Wing
The graphics below show the structure of the wake centerline behind an elliptic wing at a number of time steps after the impulsive start. The problem has been computed with an unsteady vortex lattice method.
Heaving Motion of Rectangular Wing
The figure below shows the unsteady lift coefficient of a rectangular wing in heaving motion in close proximity to the ground.
Helicopter Rotor in Forward Flight
The figure below shows the spanwise distribution of loads (lift coefficient) on a helicopter rotor blade in advancing flight. Distribution at right is for the advancing blade; distribution at left is for retreating blade. The loads on a given blade sections oscillate between the values on the advancing and retreating blade.