Study of Spontaneous Structure Formation in Granular Systems Using DEM Framework

Spontaneous cluster and pattern formation can happen in granular systems with multiple particles. Such phenomena have been observed in nature as well as in experiments. Studying these phenomena can help us understand the physics of these systems and build and validate models that can then be used in process equipment design. In this work, we investigate the spontaneous organization of granular particles in a cylindrical vessel by using discrete element method (DEM) simulations. Two different types of motion of the cylindrical vessel has been studied. In the first type of motion, the cylindrical vessel follows the horizontal circular motion, i.e., the distance between any point in the cylinder and the center of motion is fixed during the entire process. In the second type of motion, the cylindrical vessel follows the motion of an orbital shaker without self-rotation. This type of swirling motion is generated by superposing two sinusoidal vibrations in two perpendicular directions respectively. When the cylinder vessel contains a group of granular particles follows the first type of motion, the particles form a steady, symmetric structure on the side wall of the cylindrical vessel. However, if the cylindrical vessel follows the second type of motion, the particles form an asymmetric structure and becomes dynamic in nature. We examine the results of our simulations and compare to existing published experimental data to gain a better understanding of this phenomenon.