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Article
Dynamical Heterogeneity in Soft-Particle Suspensions Under Shear
Department of Physics Papers
  • Kerstin N. Nordstrom, University of Pennsylvania
  • Jerry P. Gollub, Haverford College; University of Pennsylvania
  • Douglas J. Durian, University of Pennsylvania
Document Type
Journal Article
Date of this Version
8-22-2011
Abstract
We present experimental measurements of dynamical heterogeneities in a dense system of microgel spheres, sheared at different rates and at different packing fractions in a microfluidic channel, and visualized with high-speed digital video microscopy. A four-point dynamic susceptibility is deduced from video correlations, and is found to exhibit a peak that grows in height and shifts to longer times as the jamming transition is approached from two different directions. In particular, the time for particle-size root-mean square relative displacements is found to scale as τ*∼(γΔφ4)−1, where γ is the strain rate and Δφ=|φ−φc| is the distance from the random close-packing volume fraction. The typical number of particles in a dynamical heterogeneity is deduced from the susceptibility peak height and found to scale as n*∼(γΔφ4)−0.3. Exponent uncertainties are less than ten percent. We emphasize that the same power-law behavior is found at packing fractions above and below φc. Thus our results considerably extend a previous observation of n*∼γ−0.3 for granular heap flow at fixed packing below φc. Furthermore, the implied result n*∼(τ*)0.3 compares well with the expectation from mode-coupling theory and with prior observations for driven granular systems.
Comments

Nordstrom, K.N., Gollub, J.P. & Durian, D.J. (2011). Dynamical heterogeneity in soft-particle suspensions under shear. Phys. Rev. E 84, 021403. http://dx.doi.org/10.1103/PhysRevE.84.021403

© 2011 American Physical Society

Citation Information
Kerstin N. Nordstrom, Jerry P. Gollub and Douglas J. Durian. "Dynamical Heterogeneity in Soft-Particle Suspensions Under Shear" (2011)
Available at: http://works.bepress.com/douglas_durian/9/