Flexibility in Cylinder Group Oscillated in Water

by Alan D. K. Laird,

Serial Information: Journal of the Waterways and Harbors Division, 1966, Vol. 92, Issue 3, Pg. 69-88

Document Type: Journal Paper


Forces on unyielding groups of cylinders can be approximated as the sum of forces calculated for each member with due regard to sheltering and eddy forces caused by its neighbors and to group asymmetry; yielding members require in addition consideration of the vibrational dynamics. Asymmetric groups may feel lifts and moments. Natural frequencies of the systems are excited. Each flexible cylinder behaves much as if it were alone. Its influence depends on its transfer function to the group and the transfer function of the group to the support of the group. Although forces causing vibration of a member may be a fraction of the static force corresponding to its amplitude, the fluctuating force on its support corresponds to its amplitude. There is no apparent transfer of energy between lift and drag vibrational modes. Large transverse oscillations cause large mean drag and coupling with the wake. The oscillations of groups of flexibly mounted cylinders tend to be unsynchronized.

Subject Headings: Cylinders | Vibration | Oscillations | Water management | Asymmetry | Eddy (fluid dynamics) | Natural frequency | Statics (mechanics)

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