Frequency lock-in and phase synchronization of vortex shedding behind circular cylinder due to surface waves

• Influence of harmonic surface wave on non-regular Karman vortex is studied.
• Under the influence of harmonic surface waves, frequency lock-in and synchronization of vortex shedding can arise.
• Frequency lock-in and synchronization occur if the frequency of the applied wave is twice that of the vortex shedding frequency.
• Surface waves can excite symmetric vortex street to chess-like street and completely suppress shedding behind the cylinder.
• Region of frequency lock-in is found on the plane amplitude–frequency of surface wave.

The influence of harmonic surface wave on non-regular Karman Vortex Street is investigated. In our experiments, Karman Street arises behind a vertical circular cylinder in a water flow and harmonic surface waves propagating upstream. It is found that surface waves can modify regimes of shedding in Karman Street: frequency lock-in and synchronization of vortex shedding can arise. Intensive surface waves can excite symmetric vortex street instead of chess-like street, and completely suppress shedding behind the cylinder. It is shown experimentally that such effects occur if frequency of harmonic surface wave is approximately twice higher than the frequency of vortex shedding. Region of frequency lock-in is found on the plane amplitude–frequency of surface wave.