COUPLED WAKES BEHIND 2 CIRCULAR-CYLINDERS

The wake of a pair of identical cylinders placed side by side in a uniform flow is visualized. Different flows appear when the distance between the cylinders is decreased. For large gaps, the study of the phase difference between the vortex shedding shows that locking occurs and can be associated with asymmetric flows. For small gaps, a new vortex pattern with a separated stagnant zone is visualized. Finally, a classical alternate vortex street is observed at very small gaps. An analogy with coupled oscillators is then presented in order to interpret the asymmetric regimes as beats between the wakes. © 1990 The American Physical Society.