期刊
JOURNAL OF FLUID MECHANICS
卷 925, 期 -, 页码 -出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/jfm.2021.688
关键词
dry granular material; granular mixing
资金
- National Science Foundation [CBET-1929265]
Particle segregation in flowing granular materials exhibits complex phenomena that can be described with a scaling law involving gravity-induced pressure gradient and shear rate gradient terms dependent on particle size ratio. This scaling law has been validated in various flow configurations without the need for re-fitting, and predictions regarding segregation direction based on intruder weight match experimental and computational results.
Particle segregation is common in natural and industrial processes involving flowing granular materials. Complex, and seemingly contradictory, segregation phenomena have been observed for different boundary conditions and forcing. Using discrete element method simulations, we show that segregation of a single particle intruder can be described in a unified manner across different flow configurations. A scaling relation for the net segregation force is obtained by measuring forces on an intruder particle in controlled-velocity flows where gravity and flow kinematics are varied independently. The scaling law consists of two additive terms: a buoyancy-like gravity-induced pressure gradient term and a shear rate gradient term, both of which depend on the particle size ratio. The shear rate gradient term reflects a kinematics-driven mechanism whereby larger (smaller) intruders are pushed toward higher (lower) shear rate regions. The scaling is validated, without refitting, in wall-driven flows, inclined wall-driven flows, vertical silo flows, and free-surface flows down inclines. Comparing the segregation force with the intruder weight results in predictions of the segregation direction that match experimental and computational results for various flow configurations.
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