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

通过对作用在海洋结构物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.作用在振荡圆柱上的粘性力的阻力分量有时会受到迎角的影响。2.如果考虑入射流的攻角，则作用在振荡半潜式平台上的粘性力可通过将作用在构件柱体上的粘性力相加来预测。3.定常流动使振荡圆柱的阻力系数增大，附加质量系数减小。这是由于来流的相对速度增大，Kc数增大。4.作用在不规则振动圆柱上的粘性力既受前一次振动中旋涡脱落的影响，也受当前摆动中旋涡脱落的影响。5.作用于水平浸没在规则波中的圆柱上的波浪力在很低的Kc数时迅速减小。这是因为循环流动由于粘度而绕过汽缸。6.作用在固定在规则波中的半潜式平台上的波浪力在相对较高的波高处减小。7.开发了半潜式潜水器非线性运动仿真程序。8.从静止开始作用在海崖体上的粘性力取决于圆柱从开始时的位移。9.推导了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.