In ocean engineering and coastal environmental studies, local scour around a submerged structure is a typical issue, which is affected by the inclination of the structure. To investigate the effect of inclination directions and angles on flow structure and the bed morphology, a three-dimensional numerical model of a submerged inclined cylinder was established. In this model, the hydrodynamics are solved from the RANS (Reynolds-averaged Navier–Stokes) equations closed with the RNG k-e turbulence model, while the bed morphology evolution is captured by the sediment transport model. In the case of vertical-cylinder scour, the simulation results agree well with existing laboratory experiments. In the cases of inclined-cylinder scour, the results show that the inclination direction not only changes the intensity and the location of the downflow but also modulates the pattern of the horseshoe vortex in front of the cylinder, thus influencing the local scour depth and the morphology of the bed. Compared with the case of vertical cylinder, the scour around an upstream-inclined cylinder is deeper, mainly due to the enhancement of downflow in front of the cylinder. The scour around a downstream-inclined cylinder is shallower and broader due to the weakened downflow and accelerated incoming flow. The maximum scour depth decreases with the inclination angle in the downstream-inclination case. In the upstream-inclination case, the maximum scour depth does not vary monotonously with the inclination angle, which results from a competitive effect of the horseshoe vortex and downflow in the front of the cylinder.

中文翻译：

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倾角对浸没圆柱体周围局部冲刷的影响

在海洋工程和海岸环境研究中，淹没结构周围的局部冲刷是一个典型的问题，受结构倾斜的影响。为了研究倾斜方向和角度对流动结构和床层形态的影响，建立了浸没式倾斜圆柱体的三维数值模型。在该模型中，流体动力学由 RANS（雷诺平均纳维-斯托克斯）方程求解，该方程以 RNG ke 湍流模型闭合，而床层形态演变由沉积物迁移模型捕获。在垂直圆柱冲刷的情况下，模拟结果与现有的实验室实验非常吻合。在斜圆柱冲刷的情况下，结果表明，倾斜方向不仅改变了下降流的强度和位置，而且还调节了圆柱体前马蹄形涡的形态，从而影响了局部冲刷深度和床层形态。与垂直圆柱体情况相比，上游倾斜圆柱体周围的冲刷更深，主要是由于圆柱体前方的下流增强。由于减弱的下降流和加速的进入流，下游倾斜圆柱体周围的冲刷更浅、更宽。在下游倾斜的情况下，最大冲刷深度随着倾斜角的增加而减小。在上游倾角情况下，最大冲刷深度不随倾角单调变化，