Hydrodynamic forces acting on a vertical circular cylinder moving forward with a constant velocity and making forced oscillations are measured. Wave forces on the moving cylinder in regular waves are also measured. The purpose of this investigation is improving the accuracy in estimation of the motion of an ocean structure in waves, and the reduced velocity and Keulegan-Carpenter number chosen in these experiments are larger than those in exper-iments for the structural vibration induced by the vortex.
The measured force is compared with that with no advance velocity.
The conclusions obtained are as follows;
1) Steady drag coefficient
CDY0 of a cylinder forced to sway, nondimensionalized by foward velocity
U and swaying velocity
X, does not depend on
KC number but depend slightly on the advance velocity
U.
2) Oscillating drag coefficient
CDX1 of the cylinder does not depend on
U and decrease with the decrease of
Kc number at
Kc<30.
3) Steady drag coefficient
CD0 of a cylinder forced to surge does not depend on
Kc number but depend slightly on
U.
4) Oscillating drag coefficient
CD1 of the cylinder does not depend on
U and decrease with the decrease of
Kc number at small
Kc number.
5) Steady drag coefficient
CDW0 of a cylinder in regular waves decreases with the increase of
U.
6) Oscillating drag coefficient
CDW1 is smaller than that with no advance velocity and is slightly smaller than that in steady flow.
7) Inertia coefficient
CM is almost equal to that with no advance velocity
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