Experimental data obtained from flow visualization by vortex tagging was used to verify the computational results obtained transient-state solutions of Navier-Stokes equations for vorticity during an impulsively-started flow. Good agreement was reached. The computational method was extended to `steady' state, Karman vortex street was found to occur in the wake of an NACA 0015 airfoil at 40 degrees of angle of attack with Strouhal numbers of 0.27 and 0.32 for Reynolds numbers l03 and 1.04 respectively. The forming and shedding of vortices on the lee side of a structure correspond to the cyclic decrease and increase of local pressures which cause structure fatigue.