Understanding the behaviour of water filled bodies is important from an applied engineering perspective when understanding the sea-keeping performance of certain floating platforms and vessels. Even by assuming that the deformation is negligible small in relation to the motion of the structure, these fluid-structure-fluid interactions are challenging to model, both physically and numerically, and there is a notable lack of reference data sets and studies to support the validation of this work. Most of the existing information is highly specific to certain hulls forms, or is limited to small motions. A previous study addressed this by modelling a floating cylinder (giving a more generic case) with roll and pitch motions in excess of 20°. The presented experiment expands on that work to further investigate the previously observed switch between pitch and roll in the cylinder under wave action as induced by the sloshing of the internal water volume. An additional experimental investigation, focused on a single draft, was conducted to test open research questions from the previous study. Here we show that the roll response of the water filled cylinder is repeatable, independent of the tank position and wave amplitude, provided the observation time is long enough to capture the fully developed motion response of the floating object. The mooring system used comprised four soft lines connected on two points on the cylinder. This arrangement resulted in slightly different restoring forces in different wave directions. A relative change of the wave direction by 90° led to a larger wave frequency band in which the roll motion occurred. These cases were, again, also conducted with the solid ballast. Both sets of data provide an interesting validation case for future work on water ballast inside a floating object.

中文翻译：

---

充水浮筒的滚动运动——附加实验验证

在了解某些浮动平台和船只的耐波性能时，从应用工程的角度了解充水体的行为很重要。即使假设变形相对于结构的运动小到可以忽略不计，这些流体-结构-流体相互作用在物理和数值上都难以建模，并且明显缺乏参考数据集和研究来支持这项工作的验证。大多数现有信息都高度特定于某些船体形式，或者仅限于小动作。之前的一项研究通过对滚动和俯仰运动超过 20° 的浮动圆柱体进行建模（提供更通用的案例）来解决这个问题。所提出的实验扩展了这项工作，以进一步研究先前观察到的在由内部水体积晃动引起的波浪作用下圆柱体中俯仰和滚转之间的切换。进行了一项额外的实验调查，重点是单一草案，以测试先前研究中的开放研究问题。在这里，我们展示了充水圆柱体的滚动响应是可重复的，与水箱位置和波幅无关，前提是观察时间足够长以捕获漂浮物体的完全发展的运动响应。所使用的系泊系统包括连接在圆柱体上两点的四根软绳。这种布置导致不同波浪方向的恢复力略有不同。波浪方向的相对变化90°导致发生横摇运动的更大的波浪频带。同样，这些情况也是用实心镇流器进行的。两组数据为未来在漂浮物体内压载水的工作提供了一个有趣的验证案例。