Abstract Free surface flows of granular materials in bounded axisymmetric geometries such as a cylindrical silo are poorly understood. In particular, a detailed description of the local three-dimensional velocity field and predictive models for segregation are lacking. Here, the details of the kinematics of flow in a rising conical heap formed by a centrally fed mixture of spherical particles are investigated using Discrete Element Method (DEM) simulations in a wedge-shaped geometry with periodic azimuthal boundaries. The dependence of the streamwise and surface normal velocity components on the inlet flow rate and silo radius for size-bidisperse and monodisperse mixtures of glass spheres is characterized. Compared to a wedge with frictional sidewalls, the flowing layer is much thicker on average in the axisymmetric case. Using the scalings for kinematics obtained from the DEM simulations, a modified continuum advection-diffusion-segregation model accurately predicts steady-state segregation for axisymmetric conical heap flows of size-bidisperse mixtures.

中文翻译：

---

有界圆锥堆上的轴对称颗粒流：运动学和尺寸分离

摘要 对有界轴对称几何形状（如圆柱形筒仓）中颗粒材料的自由表面流动知之甚少。特别是缺乏对局部三维速度场和偏析预测模型的详细描述。在这里，使用离散元方法 (DEM) 模拟在具有周期性方位角边界的楔形几何形状中研究由球形颗粒的中心供给混合物形成的上升锥形堆中流动的运动学细节。表征了流向和表面法向速度分量对大小双分散和单分散玻璃球混合物的入口流速和筒仓半径的依赖性。与具有摩擦侧壁的楔子相比，在轴对称情况下，流动层平均要厚得多。