Journal of Fluid Mechanics

Nonlinear forces on a horizontal cylinder beneath waves

John R.  Chaplin a1
a1 Department of Civil Engineering, University of Liverpool

Article author query
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Measurements of forces experienced by a submerged horizontal cylinder with its axis parallel to the crests in deep-water waves reveal nonlinear components with frequencies up to three times the fundamental wave frequency. The dominant nonlinear contribution to the loading is at the third order in the wave amplitude, and, for Keulegan-Carpenter numbers approaching 2, its magnitude was found to be as much as one-half that of the inertia force. It is suggested that the third-order force is associated with circulation generated by steady streaming in the oscillatory boundary layer on the cylinder. At higher Keulegan-Carpenter numbers, form drag becomes increasingly important, and velocity measurements close to the cylinder show the rapid development of the wake. Observations of nonlinear features of the transmitted waves are also discussed.

(Published Online April 20 2006)
(Received March 2 1984)
(Revised May 31 1984)