The unsteady flow separation of two-dimensional (2-D) incompressible shear flow past three identical square cylinders arranged in vee shape is studied in this paper, using theoretical structural bifurcation analysis based on topological equivalence. Through this analysis, the exact location and time of occurrence of bifurcation points (flow separation points) associated with secondary and tertiary vortices on all cylinders are studied. The existence of saddle points is also studied during primary flow separation. Different gap ratios between the downstream cylinders, s/d = 0.6–3.0 (where s is the gap between cylinders, d is the length of cylinder side) with fixed gap 2d between upstream and downstream cylinders for different shear parameter (K) values ranging from \(K=0.0\) to 0.4 are considered at Reynolds number (Re) 100. In this process, the instantaneous vorticity contours and streakline patterns, center-line velocity fluctuation, phase diagram, lift and drag coefficients are studied to confirm the theoretical results. Computations are carried out by using higher order compact finite difference scheme. Present study mainly investigates the effect of K and gap ratio on unsteady flow separation and vortex-shedding phenomenon. All the computed results very efficiently and very accurately reproduce the complex flow phenomenon. Through this study, many noticeable and interesting results are reported for the first time for this problem.

通过基于拓扑等价的理论结构分叉分析，研究了二维（2-D）不可压缩剪切流通过三个相同的呈V形的方形圆柱体的非定常流动分离。通过该分析，研究了与所有圆柱上的次级和三次涡相关的分叉点（流动分离点）的确切位置和发生时间。在一次分流过程中还研究了鞍点的存在。下游气瓶之间的间隙比不同，s / d = 0.6–3.0（其中s是气瓶之间的间隙，d是气瓶侧的长度），且间隙为2 d在雷诺数（Re）100的情况下，考虑不同的剪切参数（K）值从\（K = 0.0 \）到0.4的上游和下游圆柱之间的距离。在此过程中，瞬时涡度轮廓和条纹图案，中心线速度研究了波动，相位图，升力和阻力系数，以确认理论结果。通过使用高阶紧致有限差分方案进行计算。目前的研究主要研究钾的影响和间隙比对非稳态流动分离和涡流脱落的影响。所有计算结果都非常有效和非常准确地再现了复杂的流动现象。通过这项研究，首次针对此问题报告了许多引人注目的有趣结果。