In this paper, the surface of revolution discrete element method (SR-DEM) is introduced 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。由于旋转曲面的圆柱对称性，其绕旋转轴任意截面的几何形状保持不变。基于这一几何特征，我们提出了一种节点-截面接触算法，以实现旋转曲面颗粒间的高效接触检测。在SR-DEM框架中，接触算法采用主从模式实现：主颗粒通过其表面节点近似，而从颗粒则由绕旋转轴截面的有符号距离场（SDF）表示。这种二维与三维空间的混合建模方法既实现了高效的接触计算，又保持了代码实现的简洁性。我们随后将SR-DEM应用于颗粒-颗粒、颗粒-壁面碰撞、圆柱形容器内颗粒堆积以及转鼓内药片运动等场景，分别验证了SR-DEM对碰撞后速度、堆积孔隙率及动态休止角的预测能力。最后，我们提出了一种确定最优表面分辨率的简易方法，即通过增加表面节点数量直至表征系统的某些宏观属性达到收敛。