Motivation
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1 2 t x i t r i Motivation Experiments Particles Polystyrene beads distributed on water (mean diameter σ=0.62mm, polydisperse) Driving force Standing wave generated by a shaker Control parameter Area fraction of the particles φ Interaction between the particles Capillary force -> “cohesive” Data Trajectories projected on 2-dimensions Units time = sec. length = σ Diffusion Cross-over time arge scale convection Dynamic heterogeneity Summary Floating grains driven by standing wave & transported by convection CG method successfully subtracts the mean displacements. Crossover time of the MSD diverges near the jamming point. Time and length scales for DH diverge near the jamming point. Exponents obtained from our analysis are similar to previous Our results do not depend on the choice of CG & overlap functi * / * , r a e cr r g * 1 * , / r g r c r G a a 01 . 0 Four-point correlation function Time & length scales 3-dimensional plots of the mobility & susceptibility Fluctuation Transport by convection , , 1 , 0 N i ds s s x u t r t x t i i i t x x t x x t v t x u i d i d i , 2 / d x d e x d x d x 0 1 or Coarse Graining (CG) method Velocity field CG function Trajectories of grains Dynamic Heterogeneities in Complex Granular Flows Kuniyasu Saitoh, Ceyda Sanli, Devaraj van der Meer, and Stefan Luding University of Twente, Enschede, the Netherlands c heterogeneity (DH) is a phenomenological approach to the glass and jamming transitions, w ime and length scales show remarkable critical behaviors like critical phenomena and we saw experiments of homogeneously driven granular systems. However, the driven granular systems are s mpanied by complex flows. Therefore, the criticality in complex granular flows is the target of our s 4 . 1 * ~ 2 . 4 * ~ , 1 , 1 t r w N t q i N i a a t a a t q Q , 2 2 , , t a t a a t q t q N 9 . 3 ~ c c plateau c c C C 2 1 Mean square displacement 82 . 0 c t N i i t r N 1 2 , 1 ) ( ) ( , t r t r t r i i i Convection
description
Dynamic Heterogeneities in Complex Granular Flows Kuniyasu Saitoh , Ceyda Sanli , Devaraj van der Meer, and Stefan Luding University of Twente , Enschede , the Netherlands. Motivation. - PowerPoint PPT Presentation
Transcript of Motivation
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Motivation
Experiments ParticlesPolystyrene beads distributed on water(mean diameter σ=0.62mm, polydisperse)
Driving forceStanding wave generated by a shaker
Control parameterArea fraction of the particles φ
Interaction between the particlesCapillary force -> “cohesive”
DataTrajectories projected on 2-dimensions
Unitstime = sec. length = σ
DiffusionCross-over time
Large scale convection Dynamic heterogeneity
SummaryFloating grains driven by standing wave & transported by convection.CG method successfully subtracts the mean displacements.Crossover time of the MSD diverges near the jamming point.Time and length scales for DH diverge near the jamming point.Exponents obtained from our analysis are similar to previous works.Our results do not depend on the choice of CG & overlap functions.
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Four-point correlation function Time & length scales
3-dimensional plots of the mobility & susceptibility
Fluctuation Transport by convection
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Coarse Graining (CG) method
Velocity field
CG function
Trajectories of grains
Dynamic Heterogeneities in Complex Granular FlowsKuniyasu Saitoh, Ceyda Sanli, Devaraj van der Meer, and Stefan Luding
University of Twente, Enschede, the Netherlands
Dynamic heterogeneity (DH) is a phenomenological approach to the glass and jamming transitions, where thecharacteristic time and length scales show remarkable critical behaviors like critical phenomena and we saw the universality
in many experiments of homogeneously driven granular systems. However, the driven granular systems are sometimesaccompanied by complex flows. Therefore, the criticality in complex granular flows is the target of our study.
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Mean square displacement
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