Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA.
The Northwestern Institute on Complex Systems (NICO), Northwestern University, Evanston, Illinois 60208, USA.
Phys Rev E. 2019 Nov;100(5-1):052902. doi: 10.1103/PhysRevE.100.052902.
Size-driven particle segregation can occur when an object such as a blade moves through an otherwise static bed of granular material. Here we use discrete element method (DEM) simulations to study segregation resulting from a subsurface blade moving through a bed of size-bidisperse spherical particles. Segregation increases with each pass of the blade until a surface layer of mostly large particles forms above a small-particle layer adjacent to the bottom wall. The rate of segregation decreases with each pass so that the degree of segregation asymptotically approaches its maximum value, and the number of passes to reach a steady segregation state increases as the bed depth is increased or the blade height decreased. In shallow beds, the characteristic number of passes for segregation, τ, scales with the inverse of the granular inertial number, I. In deep beds with small blade heights, the effect of the blade is more localized to its immediate vicinity, resulting in many more passes of the blade to reach a steady segregation state, and a corresponding deviation from the shallow bed scaling of τ with I^{-1}.
当物体（如叶片）穿过静止的颗粒材料床时，可能会发生尺寸驱动的颗粒分离。在这里，我们使用离散元方法（DEM）模拟来研究由于地下叶片穿过大小双分散球形颗粒床而导致的分离。随着叶片的每一次通过，分离现象会加剧，直到在靠近底部壁的小颗粒层上方形成主要由大颗粒组成的表面层。每次通过的分离速率都会降低，以至于分离的程度会逐渐接近其最大值，并且达到稳定分离状态所需的通过次数会随着床深的增加或叶片高度的降低而增加。在浅层床中，分离的特征通过次数τ与颗粒惯性数 I 的倒数成正比。在具有小叶片高度的深床中，叶片的作用更局限于其附近区域，导致叶片需要更多次通过才能达到稳定的分离状态，并且τ与 I^{-1}的关系也偏离了浅层床的比例关系。
