Abstract The present study investigates the flow in a multi-cylinder tandem array. A primary aim is to build a framework for understanding the flow as the number of cylinders becomes large. Two-dimensional numerical simulations have been conducted of the flow past a row of identical and equispaced cylinders, at Reynolds number R e ≤ 200 , while the distance between cylinders or pitch varies in the range 1 . 1 ≤ p ≤ 10 . The number of cylinders n in the array varies between n = 2 and n = 100 . Three main regimes are identified as a function of p which are delineated by the behavior of the flow in the gap between the two most upstream cylinders, similar to the regimes in a two-cylinder array. These are a short-pitch or attached regime, with a fully attached and apparently steady flow in this gap, a medium-pitch or fluctuating regime, with some fluctuation in this gap, and a large-pitch or shedding regime, with full vortex formation similar to the wake of single-cylinder system in this gap. Large arrays show that these regimes actually occur as a geometric series, i.e. with progression downstream, the attached regime begins to fluctuate, and then form and shed vortices. This shedding regime is then followed by a region of convective instability which breaks the feedback of information upstream. The flow downstream of this convectively unstable region then goes through the same series of regimes with further downstream progression, but on a longer length scale. There is a self-similar “cascade” – development of fluctuation, established vortex shedding, convectively unstable flow – the self-similar units of which are separated by the regions of convective instability. While the length of each unit is a function of p and R e , the appearance of these units is common.

中文翻译：

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流过大量串联的气缸

摘要 本研究研究了多缸串联阵列中的流动。一个主要目的是建立一个框架来理解气缸数量变大时的流动。已经对流过一排相同且等距的圆柱的流动进行了二维数值模拟，雷诺数 Re ≤ 200，而圆柱之间的距离或间距在 1 范围内变化。1 ≤ p ≤ 10 。阵列中的圆柱数 n 在 n = 2 和 n = 100 之间变化。三个主要状态被确定为 p 的函数，它们由两个最上游气缸之间的间隙中的流动行为描述，类似于两缸阵列中的状态。这些是短间距或附着状态，在该间隙中具有完全附着且明显稳定的流动，中等间距或波动状态，这个间隙有一些波动，大螺距或脱落状态，全涡形成类似于这个间隙中的单缸系统的尾流。大阵列表明，这些状态实际上以几何级数出现，即随着下游的进展，附着的状态开始波动，然后形成和脱落涡流。这种脱落机制之后是一个对流不稳定区域，该区域破坏了上游信息的反馈。这个对流不稳定区域下游的流动然后通过相同的一系列制度，进一步向下游推进，但长度更长。有一个自相似的“级联”——波动的发展、已建立的涡旋脱落、对流不稳定的流动——它们的自相似单元被对流不稳定的区域隔开。