The effects of small bilge keels fitted at the corners of a rectangular cylinder are investigated experimentally and computationally. The freely floating cylinder is subjected to incident beam waves. As fluid viscosity affects the motion of the cylinder, a prediction of the motion response requires the solution of the Navier-Stokes equation with additional complexities coming from free-surface effects and free-body motion. The fully nonlinear problem is solved by using the Free-Surface Random-Vortex Method (Yeung and Vaidhyanathan, 1994), with recent extensions to include the effects of free-body motion (Yeung and Liao, 1999). Frequency-domain response in waves is obtained by simulating this 3DOF system in the time domain over a range of frequency. Comparison with experiments is seen to be rather satisfactory. Both experiments and time-domain solutions indicate a strong drift velocity, which is relatively insensitive to the presence or size of the keels, but dependent on the wave frequency. As expected, the keels are found to be effective in reducing the resonant modes of motion, heave and roll, near their respective resonant response peaks.
Wave-induced motion of floating cylinders fitted with bilge keels
International Journal of Offshore and Polar Engineering ; 10 , 4 ; 241-248
2000
8 Seiten, 23 Quellen
Article (Journal)
English
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