In this paper, we present the surface of revolution discrete element method (SR-DEM) to simulate systems of particles with closed surfaces of revolution. Due to the cylindrical symmetry of a surface of revolution, the geometry of any cross-section about the axis of rotation remains the same. Taking advantage of this geometric feature, a node-to-cross-section contact algorithm is proposed for efficient contact detection between particles with a surface of revolution. In our SR-DEM framework, the contact algorithm is realized in a master-slave fashion: the master particle is approximated by its surface nodes, while the slave particle is represented by a signed distance field (SDF) of the cross-section about the axis of rotation. This hybrid formulation in both 2D and 3D space allows a very efficient contact calculation yet relatively simple code implementation. We then apply SR-DEM to simulate particle-particle, particle-wall impact, granular packing in a cylindrical container, and tablets in a rotating drum, to demonstrate SR-DEM's ability to predict the post-impact velocities, packing porosity, and dynamic angle of repose, respectively. Finally, we suggest a simple approach to find an optimal surface resolution, by increasing the number of surface nodes until some of the bulk properties that could characterize the system converge.

翻译：本文提出旋转曲面离散元方法（SR-DEM），用于模拟具有闭合旋转曲面的颗粒系统。由于旋转曲面具有轴对称性，绕旋转轴任意截面的几何形状保持不变。基于这一几何特性，我们提出了一种节点-截面接触算法，用于高效检测旋转曲面颗粒间的接触。在SR-DEM框架中，该接触算法采用主从模式实现：主颗粒通过其表面节点近似，而从颗粒则用绕旋转轴截面的符号距离场（SDF）表示。这种二维与三维空间混合表达方式不仅实现了高效的接触计算，且代码实现相对简便。随后，我们将SR-DEM应用于模拟颗粒-颗粒接触、颗粒-壁面碰撞、圆柱容器内的颗粒堆积以及转鼓中的药片运动，分别验证了该方法预测碰撞后速度、堆积孔隙率及动态休止角的能力。最后，我们提出一种简单方法来确定最优表面分辨率：通过逐步增加表面节点数量，直至某些可表征系统的整体特性趋于收敛。