These 80,000 particles were used to compute the flow past an impulsively started cylinder. Figure 12.21 (Color Plate) shows the vorticity field after five time units, meaning that the cylinder has been displaced by five radii; the Reynolds number is 3000. The pair of primary eddies induced by the body's motion is clearly visible along with a number of small structures produced by the interaction of the wake with the rear portion of the cylinder. It should be noted that symmetry has been enforced in the simulation. Streamlines derived from this vorticity distribution are presented in Figure 12.22 and compared with Bouard and Coutanceau's flow visualization [Bouard:80a] obtained at the same dimensionless time and Reynolds number.
Figure 12.21: Vorticity field for Re = 3000 at time = 5.0
Figure 12.22: Comparison of Computed Streamlines with Bouard and Coutanceau Experimental Flow Visualization at Re=3000 and