Wave-free floating-body forms in shallow water and application to a very large floating structure

利用源的无波奇点和垂直偶极子组合在浅水中产生球根状二、三维体，得到了起伏振荡中的一些无波浮体形态。在满足起伏振动边界条件的计划波频率下，采用流线示踪法得到了体形。研究了无波奇点位置和水深对船体形状的影响。当水深变浅时，体型会变得纤细。用奇异分布法在二维和三维上计算得到的物体的波激力，以验证它们在计划波数处是无波的。模型实验分别在二维和三维波浪槽中进行。在规则波中测量得到的无波体的波激力。由起伏激励振幅响应函数估计的无波频率与理论基本一致，但略高，这可能与水的黏度等非线性效应有关。最后，提出了将这种无波体应用于超大型半潜式浮体结构的建议。

Some wave-free floating-body forms in heaving oscillation are obtained by using a wave-free singularity of source and vertical dipole combination to generate bulbous-shaped two-and three-dimentional bodies in shallow water. Body forms are obtained by the streamline tracing method at a planned wave frequency, where the body boundary condition of heaving oscillation is satisfied.Effects of location of the wave-free singularity and water depth on the body-form are studied. Body forms become slender as water depth becomes shallow. Wave exciting forces of obtained bodies are calculated by the singularity distribution method in two-and three-dimentions to verify that they become wave-free at the planned wave-number.Model experiments were conducted in 2D and 3D wave tanks. Wave exciting forces of obtained wave-free bodies were measured in regular waves. Wave-free frequency estimated by amplitude reaponse function of heaving excitation is almost same as the theory but a little bit higher, which may be attributed to nonlinear effects such as viscosity of water. Finally, some proposal are made to apply such a wave-free body to a very large floating structure (VLFS) of semi-submersible type.