This study is to discuss the wave force acting on a submerged sphere due to the diffracted wave based on a numerical analysis. The hybrid method is employed to calculate the velocity potential of the diffracted wave.
The added mass coefficient, the force coefficients, the dominant range of the diffraction force are investigated in relation to the wave height distribution and non-dimensional parameters such as the relative sphere radius to the wave length,
ka, the relative sphere diameter to water depth,
D/
h, and the relative submergence,
d/
h. The wave diffraction is governed by
ka,
D/
h and
d/
h. The effect of wave diffraction to the vertical wave force is generally larger than that to the horizontal one. The added mass coefficient becomes larger with an increment of
D/
h and with decreasing of
d/
h for the same
ka. When the change of wave heights is less than 5%, the diffracted wave has little effect to the wave force. The range in which the diffraction theory is applied in calculating the wave force is given graphically as a function of
ka,
d/
h and
D/
h.
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