The effect of a plane boundary on wave induced forces acting on a submerges cylinder.

Abstract

The in-line and transverse forces acting on cylinders of 1.0 inch to 2.5 inches diameter placed near a plane wall in a harmonically oscillating flow have been measured. The drag and inertia coefficients C(d), and C(m) for the in-line force and the lift coefficients C(1A) and C(1T) for the transverse forces away and toward the wall, respectively, have been determined as a function of the relative gap e/D between the wall and the cylinder and the period parameter V(m)T/D. The relative gap ranged from 0.0143 to unity and the period parameter from zero to 35. In the subcritical range where these experiments have been performed, the effect of the Reynolds number, which ranged from 4,000 to 30,000, was found to be secondary and certainly obscured by the excellent correlation provided by the period parameter. The frequency of the transverse force was found to range from one to five times the frequency of oscillation of the harmonic motion, but a dominant frequency of twice the oscillation frequency was seen over most of the values of V(m)T/D.