Publication Detail

Dimensionless Parameters Important to the Prediction of Vortex-induced Vibration of Long, Flexible Cylinders in Ocean Currents.

1991
51 pp.
MITSG 91-13

The design of moorings, ROV tethers, pipelines, and petroleum drilling and production risers all depend on the expected magnitude and frequency of vortex-induced vibration. Lock-in usually results in the largest amplitudes of vibration and the largest mean drag coefficients; this paper examines the parameters which have greatest influence over the occurrence of lock-in for flexible cylinders. Case studies drawn from 15 years of field and laboratory experiments demonstrate and explain why the flow-induced vibration of long cylinders in ocean currents varies from single mode lock-in to broad-band random vibration. When consideration of a few dimensionless parameters reveals that multiple mode response without lock-in is likely to occur, hydrodynamic damping has a powerful influence on dynamic response, and the simple product of the total damping ratio and the mode number allows anticipation of the whole range of response behavior, from the wave propagation properties of infinite length cables to the standing wave features of shore cylinders.

type: Technical reports

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