The paper investigates the role of geometrical asymmetric modifications of a rectangular flat-backed body on the properties of the recirculating flow at a Reynolds number $$Re=1.8\times 10^5$$ . The reference model has two reflectional symmetries denoted $$s_y$$ and $$s_z$$ in both spanwise directions. The flow is subjected to the static instability that leads to two mirrored wake states breaking the symmetry $$s_y$$ . Two families of geometrical variation of the fore-body and after-body are studied, each breaking one of the reflectional symmetries of the reference model. Geometrical modifications that preserve $$s_y$$ evidence possibilities of bistable dynamics suppression although the static instability persists. Geometrical modifications that do not preserve $$s_y$$ produces a large unbalance of both wake states in accordance to recent observations on real cars (Bonnavion et al. in J Wind Eng Ind Aerodyn 184:77–89, 2019). Results offer perspectives for potential drag reduction induced by appropriate coupling of bluff body geometry and wake state selection.

中文翻译：

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三维非对称钝体循环流动的研究

该论文研究了矩形平背体的几何不对称修改对雷诺数 $$Re=1.8\times 10^5$$ 下再循环流特性的作用。参考模型在两个展向方向上具有两个反射对称性，分别表示为 $$s_y$$ 和 $$s_z$$。流动受到静态不稳定性的影响，导致两个镜像的尾流状态破坏对称性 $$s_y$$ 。研究了前体和后体的两个几何变化族，每个族都破坏了参考模型的反射对称性之一。尽管静态不稳定性持续存在，但保留 $$s_y$$ 的几何修改证明了双稳态动力学抑制的可能性。根据最近对真实汽车的观察（Bonnavion 等人在 J Wind Eng Ind Aerodyn 184:77–89, 2019 中），不保留 $$s_y$$ 的几何修改会产生两种尾流状态的严重不平衡。结果为通过适当耦合钝体几何形状和尾流状态选择引起的潜在减阻提供了前景。