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Full-Text Articles in Physical Sciences and Mathematics
Statistics Of Bubble Rearrangement Dynamics In A Coarsening Foam, Alex Gittings, Douglas J. Durian
Statistics Of Bubble Rearrangement Dynamics In A Coarsening Foam, Alex Gittings, Douglas J. Durian
Douglas J. Durian
We use speckle-visibility spectroscopy to measure the time dependence of bubble rearrangement events that are driven by coarsening in an aqueous foam. This technique gives the time trace for the average scattering site speed within a prescribed volume of the sample. Results are analyzed in terms of distributions of event times, event speeds, and event displacements. The distribution of rest times between successive events is also measured; comparison with diffusing-wave spectroscopy results shows that the spatial structure of a typical event consists of a core of only a few bubbles which undergo topology change plus a surrounding shell of bubbles …
Geometry Dependence Of The Clogging Transition In Tilted Hoppers, C. C. Thomas, Douglas J. Durian
Geometry Dependence Of The Clogging Transition In Tilted Hoppers, C. C. Thomas, Douglas J. Durian
Douglas J. Durian
We report the effects of system geometry on the clogging of granular material flowing out of flat-bottomed hoppers with variable aperture size D and with variable angle θ of tilt of the hopper away from horizontal. In general, larger tilt angles make the system more susceptible to clogging. To quantify this effect for a given θ, we measure the distribution of mass discharged between clogging events as a function of aperture size and extrapolate to the critical size at which the average mass diverges. By repeating for different angles, we map out a clogging phase diagram as a function of …
Dynamics Of Gas-Fluidized Granular Rods, L. J. Daniels, Y. Park, Thomas C. Lubensky, Douglas J. Durian
Dynamics Of Gas-Fluidized Granular Rods, L. J. Daniels, Y. Park, Thomas C. Lubensky, Douglas J. Durian
Douglas J. Durian
We study a quasi-two-dimensional monolayer of granular rods fluidized by a spatially and temporally homogeneous upflow of air. By tracking the position and orientation of the particles, we characterize the dynamics of the system with sufficient resolution to observe ballistic motion at the shortest time scales. Particle anisotropy gives rise to dynamical anisotropy and superdiffusive dynamics parallel to the rod’s long axis, causing the parallel and perpendicular mean-square displacements to become diffusive on different time scales. The distributions of free times and free paths between collisions deviate from exponential behavior, underscoring the nonthermal character of the particle motion. The dynamics …
Bubble Statistics And Coarsening Dynamics For Quasi-Two-Dimensional Foams With Increasing Liquid Content, A. E. Roth, C. D. Jones, Douglas J. Durian
Bubble Statistics And Coarsening Dynamics For Quasi-Two-Dimensional Foams With Increasing Liquid Content, A. E. Roth, C. D. Jones, Douglas J. Durian
Douglas J. Durian
We report on the statistics of bubble size, topology, and shape and on their role in the coarsening dynamics for foams consisting of bubbles compressed between two parallel plates. The design of the sample cell permits control of the liquid content, through a constant pressure condition set by the height of the foam above a liquid reservoir. We find that in the scaling regime, all bubble distributions are independent not only of time, but also of liquid content. For coarsening, the average rate decreases with liquid content due to the blocking of gas diffusion by Plateau borders inflated with liquid; …
Effective Temperatures And Activated Dynamics For A Two-Dimensional Air-Driven Granular System On Two Approaches To Jamming, Adam Ross Abate, Douglas J. Durian
Effective Temperatures And Activated Dynamics For A Two-Dimensional Air-Driven Granular System On Two Approaches To Jamming, Adam Ross Abate, Douglas J. Durian
Douglas J. Durian
We present experiments on several distinct effective temperatures in a granular system at a sequence of increasing packing densities and at a sequence of decreasing driving rates. This includes single-grain measurements based on the mechanical energies of both the grains and an embedded oscillator, as well as a collective measurement based on the Einstein relation between diffusivity and mobility, which all probe different time scales. Remarkably, all effective temperatures agree. Furthermore, mobility data along the two trajectories collapse when plotted vs effective temperature and exhibit an Arrhenius form with the same energy barrier as the microscopic relaxation time.
Topological Persistence And Dynamical Heterogeneities Near Jamming, Adam Ross Abate, Douglas Durian
Topological Persistence And Dynamical Heterogeneities Near Jamming, Adam Ross Abate, Douglas Durian
Douglas J. Durian
We introduce topological methods for quantifying spatially heterogeneous dynamics, and use these tools to analyze particle-tracking data for a quasi-two-dimensional granular system of air-fluidized beads on approach to jamming. In particular, we define two overlap order parameters, which quantify the correlation between particle configurations at different times, based on a Voronoi construction and the persistence in the resulting cells and nearest neighbors. Temporal fluctuations in the decay of the persistent area and bond order parameters define two alternative dynamic four-point susceptibilities XA(τ) and XB(τ), well suited for characterizing spatially heterogeneous dynamics. These are analogous to the standard four-point dynamic susceptibility …
Coarsening Of A Two-Dimensional Foam On A Dome, A. E. Roth, C. D. Jones, Douglas J. Durian
Coarsening Of A Two-Dimensional Foam On A Dome, A. E. Roth, C. D. Jones, Douglas J. Durian
Douglas J. Durian
In this paper we report on bubble growth rates and on the statistics of bubble topology for the coarsening of a dry foam contained in the narrow gap between two hemispheres. By contrast with coarsening in flat space, where six-sided bubbles neither grow nor shrink, we observe that six-sided bubbles grow with time at a rate that depends on their size. This result agrees with the modification to von Neumann’s law predicted by J. E. Avron and D. Levine [Phys. Rev. Lett. 69, 208 (1992)]. For bubbles with a different number of sides, except possibly seven, there is too much …
Effects Of Particle Shape On Growth Dynamics At Edges Of Evaporating Drops Of Colloidal Suspensions, Peter Yunker, Matthew Lohr, Tim Still, Alexei Borodin, Douglas Durian, Arjun Yodh
Effects Of Particle Shape On Growth Dynamics At Edges Of Evaporating Drops Of Colloidal Suspensions, Peter Yunker, Matthew Lohr, Tim Still, Alexei Borodin, Douglas Durian, Arjun Yodh
Douglas J. Durian
We study the influence of particle shape on growth processes at the edges of evaporating drops. Aqueous suspensions of colloidal particles evaporate on glass slides, and convective flows during evaporation carry particles from drop center to drop edge, where they accumulate. The resulting particle deposits grow inhomogeneously from the edge in two dimensions, and the deposition front, or growth line, varies spatiotemporally. Measurements of the fluctuations of the deposition front during evaporation enable us to identify distinct growth processes that depend strongly on particle shape. Sphere deposition exhibits a classic Poisson-like growth process; deposition of slightly anisotropic particles, however, belongs …
Dynamical Heterogeneity In Soft-Particle Suspensions Under Shear, Kerstin N. Nordstrom, Jerry P. Gollub, Douglas J. Durian
Dynamical Heterogeneity In Soft-Particle Suspensions Under Shear, Kerstin N. Nordstrom, Jerry P. Gollub, Douglas J. Durian
Douglas J. Durian
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 …
Making A Frothy Shampoo Or Beer, Douglas Durian, Srinivasa R. Raghavan
Making A Frothy Shampoo Or Beer, Douglas Durian, Srinivasa R. Raghavan
Douglas J. Durian
No abstract provided.
Shape And Erosion Of Pebbles, Douglas Durian, H. Bideaud, P. Duringer, A. P. Schröder, C. M. Marques
Shape And Erosion Of Pebbles, Douglas Durian, H. Bideaud, P. Duringer, A. P. Schröder, C. M. Marques
Douglas J. Durian
The shapes of flat pebbles may be characterized in terms of the statistical distribution of curvatures measured along their contours. We illustrate this method for clay pebbles eroded in a controlled laboratory apparatus, and also for naturally occurring rip-up clasts formed and eroded in the Mont St.-Michel bay. We find that the curvature distribution allows finer discrimination than traditional measures of aspect ratios. Furthermore, it connects to the microscopic action of erosion processes that are typically faster at protruding regions of high curvature. We discuss in detail how the curvature may be reliably deduced from digital photographs.
Temperature-Pressure Scaling For Air-Fluidized Grains Near Jamming, L. J. Daniels, T. K. Haxton, N. Xu, Andrea J. Liu, Douglas J. Durian
Temperature-Pressure Scaling For Air-Fluidized Grains Near Jamming, L. J. Daniels, T. K. Haxton, N. Xu, Andrea J. Liu, Douglas J. Durian
Douglas J. Durian
We present experiments on a monolayer of air-fluidized beads in which a jamming transition is approached by increasing pressure, increasing packing fraction, and decreasing kinetic energy. This is accomplished, along with a noninvasive measurement of pressure, by tilting the system and examining behavior versus depth. We construct an equation of state and analyze relaxation time versus effective temperature. By making time and effective temperature dimensionless using factors of pressure, bead size, and bead mass, we obtain a good collapse of the data but to a functional form that differs from that of thermal hard-sphere systems. The relaxation time appears to …
What Is In A Pebble Shape?, Douglas J. Durian, H. Bideaud, P. Duringer, A. Schröder, F. Thalmann, C. M. Marques
What Is In A Pebble Shape?, Douglas J. Durian, H. Bideaud, P. Duringer, A. Schröder, F. Thalmann, C. M. Marques
Douglas J. Durian
We propose to characterize the shapes of flat pebbles in terms of the statistical distribution of curvatures measured along the pebble contour. This is demonstrated for the erosion of clay pebbles in a controlled laboratory apparatus. Photographs at various stages of erosion are analyzed, and compared with two models. We find that the curvature distribution complements the usual measurement of aspect ratio, and connects naturally to erosion processes that are typically faster at protruding regions of high curvature.
Approach To Jamming In An Air-Fluidized Granular Bed, Adam Ross Abate, Douglas J. Durian
Approach To Jamming In An Air-Fluidized Granular Bed, Adam Ross Abate, Douglas J. Durian
Douglas J. Durian
Quasi-two-dimensional bidisperse amorphous systems of steel beads are fluidized by a uniform upflow of air, so that the beads roll on a horizontal plane. The short-time ballistic motion of the beads is stochastic, with non-Gaussian speed distributions and with different average kinetic energies for the two species. The approach to jamming is studied as a function of increasing bead area fraction and also as a function of decreasing air speed. The structure of the system is measured in terms of both the Voronoi tessellation and the pair distribution function. The dynamics of the system is measured in terms of both …
Projectile Interactions In Granular Impact Cratering, E. L. Nelson, Hiroaki Katsuragi, Patrick Mayor, Douglas J. Durian
Projectile Interactions In Granular Impact Cratering, E. L. Nelson, Hiroaki Katsuragi, Patrick Mayor, Douglas J. Durian
Douglas J. Durian
We present evidence for the interactions between a ball and the container boundaries, as well as between two balls, that are mediated by the granular medium during impact cratering. The presence of the bottom boundary affects the final penetration depth only for low drop heights with shallow filling, in which case, surprisingly, the penetration becomes deeper. By contrast the presence of the sidewall causes less penetration and also an effective repulsion. Repulsion is also found for two balls dropped side by side.
Avalanche Statistics And Time-Resolved Grain Dynamics For A Driven Heap, Adam Ross Abate, Hiroaki Katsuragi, Douglas J. Durian
Avalanche Statistics And Time-Resolved Grain Dynamics For A Driven Heap, Adam Ross Abate, Hiroaki Katsuragi, Douglas J. Durian
Douglas J. Durian
We probe the dynamics of intermittent avalanches caused by steady addition of grains to a quasi-twodimensional heap. To characterize the time-dependent average avalanche flow speed v(t), we image the top free surface. To characterize the grain fluctuation speed δv(t), we use speckle-visibility spectroscopy. During an avalanche, we find that the fluctuation speed is approximately one-tenth the average flow speed, δv ≈ 0.1v, and that these speeds are largest near the beginning of an event. We also find that the distribution of event durations is peaked, and that event sizes are correlated with the time interval since the end of the …
Centrifugal Compression Of Soft Particle Packings: Theory And Experiment, Kerstin Nordstrom, Emilie Verneuil, Wouter Ellenbroek, Tom Lubensky, Jerry Gollub, Douglas Durian
Centrifugal Compression Of Soft Particle Packings: Theory And Experiment, Kerstin Nordstrom, Emilie Verneuil, Wouter Ellenbroek, Tom Lubensky, Jerry Gollub, Douglas Durian
Douglas J. Durian
An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain—for example as required by packings composed of deformable but incompressible particles. Experimental data are presented for the centrifugal compression of thermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For small radial acceleration, the results are consistent with Hertzian elasticity, and are analyzed in terms of the Young elastic modulus of the bead material. For large radial acceleration, the …