Abstract The inhomogeneous distributions of inertial particles in the unsteady flow around a wetted circular cylinder at R e = 100 were investigated in one-way coupled three-dimensional numerical simulations. The Karman vortex cells determine the local patterns of particle clustering. In the vicinity of the cylinder, a bow shock-like clustering was explored via Voronoi diagrams. The shape of the bow shock in terms of width and thickness strongly depends on Stokes number, Sk. For high-Sk particles, the bow shock was wider and less affected by the vortex shedding in the near wake and thus extended further downstream. We tracked low-Sk particles in a steady potential flow aimed at mimicking the viscous flow field close to the cylindrical surface. The converging tendency of the particle trajectories at the upstream of the cylinder supported the appearance of a bow shock. Furthermore, we analysed the trajectory of a Sk=0.1 particle in viscous flow, wherein the direction of the perpendicular component of the Stokes drag force was altered from outwards to inwards at the inflection point of the trajectory. This observation suggests that the centrifugal mechanism makes particle trajectories converge and thereby contributes to the formation of the bow shock.

中文翻译：

---

载有颗粒的湿圆柱流中的弓形激波聚类

摘要 通过单向耦合三维数值模拟研究了在R e = 100 时绕湿圆柱体的非定常流动中惯性粒子的不均匀分布。卡门涡旋单元决定了粒子聚集的局部模式。在圆柱体附近，通过 Voronoi 图探索了类似弓形激波的聚类。就宽度和厚度而言，弓形激波的形状很大程度上取决于斯托克斯数 Sk。对于高 Sk 粒子，弓形激波更宽，受近尾流涡旋脱落的影响较小，从而进一步向下游延伸。我们在稳定的势流中跟踪低 Sk 粒子，旨在模拟接近圆柱表面的粘性流场。圆柱上游粒子轨迹的会聚趋势支持了弓形激波的出现。此外，我们分析了粘性流中 Sk=0.1 粒子的轨迹，其中斯托克斯阻力的垂直分量的方向在轨迹的拐点处由外向内改变。这一观察表明离心机制使粒子轨迹收敛，从而有助于弓形激波的形成。