Flow around an oriented cube is experimentally studied using particle image velocimetry measurements. The cube is rigidly suspended and oriented at an angle of ${45}^{\circ }$ with respect to the freestream flow. Instantaneous and mean flow fields in the wake have been examined at 16 different values of Reynolds numbers between 500 and $50000$. Vorticity identified using swirling strength shows a chaotic wake at higher Re. A wider wake and a longer wake length are noted as compared to flow around a normal cube. The wake width collapses to nearly the same value for all Re beyond the wake length. Unlike a cube, an oriented cube has a recirculation region with multiple peaks for velocity deficit, which is a signature of many smaller eddies present in the wake. The range of investigated Reynolds numbers shows behavioral changes in the wake, hinting at the possibility of critical Reynolds numbers (or different regimes) based on a maximum velocity deficit, maximum vorticity magnitude, and energy content of the first mode extracted using proper orthogonal decomposition. Proper orthogonal decomposition has been used to understand the contribution of different modes in the formation of coherent structures in the wake. An oriented cube is an extreme case for nonspherical objects and has marked differences from the wake of a cube and other regular-shaped objects. The present work is an attempt to provide an understanding of and improve upon the scarce investigation performed for the wake of an oriented cube.

中文翻译：

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雷诺数介于 500 和 50 000 之间的 a45∘取向立方体周围流动的实验研究

使用粒子图像测速测量实验研究了定向立方体周围的流动。立方体刚性悬挂并以${45}^{\circ }$关于自由流。已经在 500 和 500 之间的 16 个不同雷诺数值下检查了尾流中的瞬时和平均流场。$50000$. 使用旋流强度确定的涡度显示了较高 Re 下的混乱尾流。与围绕正常立方体的流动相比，注意到更宽的尾流和更长的尾流长度。对于超出尾流长度的所有 Re，尾流宽度会收缩到几乎相同的值。与立方体不同，定向立方体有一个再循环区域，该区域具有多个速度赤字峰值，这是尾流中存在的许多较小涡流的特征。研究的雷诺数的范围显示了尾流中的行为变化，暗示了基于最大速度赤字、最大涡量大小和使用适当正交分解提取的第一模式的能量含量的临界雷诺数（或不同制度）的可能性。适当的正交分解已被用于理解不同模式在尾迹相干结构形成中的贡献。定向立方体是非球形物体的极端情况，与立方体和其他规则形状物体的尾流有显着差异。目前的工作是试图提供对定向立方体尾流进行的稀有调查的理解和改进。