Abstract Vortex flow around multiple columns of finite length is ubiquitous in engineering. The present work focuses on the basic fluid physics in terms of the vortex shedding flow patterns and their dependence on structural configurations and flow parameters. Though widely documented in the literature, there is no consensus on certain aspects of the wake characteristics immediately behind the obstacles for a multi-column structure at a relative high Reynolds number range. A comprehensive set of numerical simulations has been conducted to investigate the flow interactions with four square section shaped columns in a diamond configuration, which is complimented by experiments using particle image velocimetry and force measurements in a physical model with Reynolds numbers varying from 3.7 × 10 4 to 6.0 × 10 4 . Horizontal structural members called pontoons were added near the end of the columns to alter the interactions with the surrounding fluid. This work reveals further insights of the fluid physics including the interactions of the vortex shedding processes due to the multi-columns and pontoons. The pontoons are seen blocking the vortices shed from the free end of the column by pushing the recirculation region further away from the free end of each column. In addition to the vortex shedding period being increased, further examination of the wake region indicates that the vortex street tends to be tidier and more structured by adding the pontoons to a basic multi-column structure. The findings will lead to better understanding in vortex shedding fluid physics and improved design in new offshore structure development such as deep-draft semi-submersibles and tension leg platforms.

中文翻译：

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有或无水平连接的多柱结构的涡脱落特性

摘要 围绕多个有限长度柱的涡流在工程中普遍存在。目前的工作侧重于涡旋脱落流型及其对结构配置和流动参数的依赖性方面的基本流体物理学。尽管在文献中得到了广泛的记录，但对于在相对较高的雷诺数范围内多柱结构的障碍背后的尾流特征的某些方面并没有达成共识。已经进行了一套全面的数值模拟来研究与菱形配置中的四个方形截面柱的流动相互作用，这得到了在雷诺数从 3.7 × 10 4 不等的物理模型中使用粒子图像测速和力测量的实验的补充到 6.0 × 10 4 。在柱子的末端附近添加了称为浮筒的水平结构构件，以改变与周围流体的相互作用。这项工作揭示了流体物理学的进一步见解，包括由于多柱和浮筒引起的涡旋脱落过程的相互作用。可以看到浮筒通过将再循环区域推离每个柱的自由端更远来阻挡从柱的自由端脱落的涡流。除了涡流脱落期增加之外，对尾流区域的进一步检查表明，通过将浮筒添加到基本的多柱结构中，涡街趋于更整洁和更有条理。