Vortex shedding over five in-line cylinders

The flow about cylinders in line organizes itself into vortices which form and shed at distinct natural frequencies. This paper presents a detailed examination of the phenomena associated with this organization and the different natural frequencies involved. Conclusions are drawn from data gathered from velocity fluctuations in the flow over five in-line cylinders. It is proved that different patterns of vortex shedding coexist and that, at diffrent spacings and Reynolds numbers, one may dominate the other. The most significant mechanism is found to be gap shedding, namely, alternate vortex shedding between the cylinder gaps, which dominates the flow over a pentad for all the spacings tested. It is conjectured that such mechanisms are present in flows through banks of cylinders and could be excited if driven by structural vibrations.