Three-dimensional numerical simulations were performed to study the effects of flow direction and flow velocity on the flow regime behind a curved pipe represented by a curved circular cylinder. The cylinder is based on a previous study and consists of a quarter segment of a ring and a horizontal part at the end of the ring. The cylinder was rotated in the computational domain to examine five incident flow angles of 0–180$°$ with 45$°$ intervals at Reynolds numbers of 100 and 500. The detailed wake topologies represented by ${\lambda }_2$ criterion were captured using a Large Eddy Simulation (LES). The curved cylinder leads to different flow regimes along the span, which shows the three-dimensionality of the wake field. At a Reynolds number of 100, the shedding was suppressed after flow angle of 135$°$, and oblique flow was observed at 90$°$. At a Reynolds number of 500, vortex dislocation was detected at 90$°$ and 135$°$. These observations are in good agreement with the three-dimensionality of the wake field that arose due to the curved shape.

进行了三维数值模拟，研究了流动方向和流速对以弯曲圆柱体为代表的弯曲管后的流动状态的影响。该圆柱体是基于以前的研究，由一个环的四分之一部分和一个位于环末端的水平部分组成。在计算域中旋转圆柱体以检查0-180°的五个入射流角$°$ 与45$°$ 雷诺数分别为100和500的时间间隔。 ${\lambda }_2$使用大涡模拟（LES）捕获标准。弯曲的圆柱体导致跨度不同的流态，这显示了尾流场的三维性。雷诺数为100时，流动角为135后，脱落被抑制$°$，并且在90度观察到斜流$°$。雷诺数为500时，在90处检测到涡旋位错$°$ 和135$°$。这些观察结果与由于弯曲形状而产生的尾波场的三维性非常吻合。