Abstract—

A high-order discontinuous Galerkin method is employed to study the evolution of the flow structure in the gap and near wake of two tandem cylinders in the alternating in the gap (AG) regime. The transient characteristics of the flow, vorticity, and pressure fields, the transient circumferential pressure distribution, and the streamwise velocity along the centerline of the wake are studied under a Reynolds number of 200 and a pitch ratio of 2.3. The results show that the gap-flow occurs between the two tandem cylinders in the AG regime, and the gap-flow interacts with quasistatic vortices in the gap to cause unilateral or bilateral reattachment of the separated shear layer. In addition, under the influence of the gap-flow, a near-wake vortex is generated behind the downstream cylinder, which significantly affects the length of the recirculation bubble. Finally, the physical mechanism of reattachment of the shear layer and the generation of gap-flow in the AG regime are discussed.

中文翻译：

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AG 机制中两个串联圆柱体间隙和近尾流中流动结构的演变

摘要——

采用高阶不连续伽辽金方法研究间隙 (AG) 状态下交替的两个串联圆柱体的间隙和近尾流中流动结构的演变。在雷诺数为200、螺距比为2.3的条件下，研究了流场、涡度和压力场的瞬态特性、瞬态周向压力分布以及沿尾流中心线的流向速度。结果表明，在AG状态下，两个串联圆柱之间发生间隙流，间隙流与间隙中的准静态涡流相互作用，导致分离的剪切层单侧或双侧重新附着。此外，在间隙流的影响下，下游圆柱体后方产生近尾涡，这会显着影响再循环气泡的长度。最后，讨论了剪切层重新附着的物理机制和 AG 状态下间隙流的产生。