Evidence of two effects in the size segregation process in dry granular media.
Evidence of two effects in the size segregation process in dry granular media.
复制标题
干燥颗粒介质中尺寸分离过程的两种影响的证据。
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
N. Thomas
中科院分区：
文献类型：
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作者：
G. Félix;N. Thomas
在半填充的转鼓中，等密度颗粒的尺寸偏析形成了大颗粒的环形图案，其位置从外围到中心连续变化，具体取决于颗粒之间的尺寸比[N.托马斯，物理学家。修订版 E 62, 961 (2000)]。对于小尺寸比（通常< 5）位置。具有中间半径的圆的存在表明流内的中间水平的分离是可能的。在本文中，我们通过实验研究了半满转鼓和其他装置（溜槽流、堆）中不同密度和尺寸的颗粒的分离。在转鼓中，隔离环的位置从外围到中心不断变化，并且对尺寸（从 1 到 33）和密度（从 0.36 到 4.8）比率非常敏感。最密集的大珠子分布在靠近中心的圆圈上，最轻的大珠子分布在靠近外围的圆圈上。因此，我们发现，对于任何示踪剂，其质量过剩（仅由于尺寸过剩、密度过剩或两者兼而有之）都会导致示踪剂的深层内部偏析。推离过程使任何类型的重珠子向下移动，而已知尺寸过大的珠子会通过动态筛分过程将大珠子推向表面。中间环处的每次偏析对应于这些质量和几何效应之间的平衡。流中的偏析水平由两种效应的强度之比决定。
In a half-filled rotating drum, the size segregation of particles of equal density builds a ring pattern of the large particles, whose location continuously varies from the periphery to the center depending on the size ratio between particles [N. Thomas, Phys. Rev. E 62, 961 (2000)]. For small size ratios (typically < 5) position. The existence of circles with an intermediate radius shows that the segregation at an intermediate level within a flow is possible. In this paper, we experimentally study the segregation of particles of different densities and sizes in a half-filled rotating drum and other devices (chute flow, pile). In the drum, the location of the segregated ring continuously varies from the periphery to the center and is very sensitive to both the size (from 1 to 33) and density (from 0.36 to 4.8) ratios. The densest large beads segregate on a circle close to the center, the lightest large beads on a circle close to the periphery. Consequently, we found that for any tracer, its excess of mass, due to only a size excess, a density excess, or both, leads to a deep inside segregation of the tracer. There is a push-away process that makes heavy beads of any type go downwards, while the excess of size is already known to push large beads towards the surface, by a dynamical sieving process. Each segregation at an intermediate ring corresponds to a balance between these mass and geometrical effects. The segregation level in the flow is determined by the ratio of the intensities of both effects.