In the present study we compare the hydrodynamic forces
acting on circular cylinders oscillating in still fluid with corresponding oscillations transverse to a free stream. We find that at small amplitudes of motion the time history of the total force acting in the direction of oscillation in the presence of a free stream is virtually the same as in still fluid and in very good agreement with Stokes–Wang analytical solutions. However, the flow patterns around the cylinders that generate the consistent force history are remarkably disparate
