Researches on Wave Forces Acting on Offshore Structures and Motions in Waves

通过对作用在近海结构上的波浪力及其在波浪中的响应的研究，得出了以下结论。1. 作用在振动圆柱上的粘性力的阻力分量有时会影响迎角。2. 如果考虑入射气流的攻角，则可以通过将作用在构件圆柱体上的粘性力相加来预测作用在振荡半潜器上的粘性力。3. 定常流动增加了振荡气缸的阻力系数，降低了附加质量系数。这是由于入射流相对速度的增加和Kc数的增加。4. 作用在不规则振荡圆柱体上的粘滞力不仅受到先前振荡中涡脱落的影响，而且受到当前摆动中涡脱落的影响。5. 在规则波中水平淹没的圆柱体所受的波浪力在Kc数很低时迅速减小。这是因为绕筒流动的循环由于粘度的关系。6. 固定在规则波浪中的半潜器所受的波浪力在较高的波高时减小。7. 编制了半潜船非线性运动仿真程序。8. 作用在钝体上的粘性力从静止开始取决于圆柱体从开始时的位移。9. 推导了一种低频振荡阻尼的预测方法。

Through studies on wave forces acting on an offshore structure and on response of it in waves following conclusions have been obtained. 1. Drag component of viscous forces acting on an oscillating cylinder is sometimes affected the angle of attack. 2. Viscous forces acting on an oscillating semisubmersible can be predicted by summing up the viscous forces acting on the member cylinders if the angle of attack for the incident flow is taken into account. 3. Steady flow increases the drag coefficient and decreases the added mass coefficient of an oscillating cylinders. This is because increase of the relative velocity of the incident flow and increase of Kc number. 4. Viscous forces acting on an irregularly oscillating cylinder are affected by vortices shedding in previous oscillations as well as vortex shedding in the present swing. 5. Wave forces acting on a cylinder submerged horizontally in regular waves rapidly decreases at very low Kc number. This is because the circulation flow rounding the cylinder due to viscosity. 6. Wave forces acting on a semisubmersible fixed in regular waves decreases at relatively high wave height. 7. A simulation program for non-linear motions of a semisubmergible has been developed. 8. Viscous forces acting on a bluff body starting from rest depend on the displacement of the cylinder from the start. 9. A prediction method of the damping for low frequency oscillation has been derived.