17 research outputs found
Dissipation and Rheology of Sheared Soft-Core Frictionless Disks
We use numerical simulations to investigate the effect of different
dissipative models on the shearing rheology of massive soft-core frictionless
disks in two dimensions. We show that the presence of Newtonian (overdamped) vs
Bagnoldian (inertial) rheology is related to the formation of large connected
clusters of disks, and that sharp transitions may exist between the two as
system parameters vary. In the limit of strongly inelastic collisions, we find
that rheological curves collapse to a well-defined limit when plotted against
an appropriate dimensionless strain rate.Comment: 6 pages, 5 figures, revised to published versio
Glassiness, Rigidity and Jamming of Frictionless Soft Core Disks
The jamming of bi-disperse soft core disks is considered, using a variety of
different protocols to produce the jammed state. In agreement with other works,
we find that cooling and compression can lead to a broad range of jamming
packing fractions , depending on cooling rate and initial
configuration; the larger the degree of big particle clustering in the initial
configuration, the larger will be the value of . In contrast, we find
that shearing disrupts particle clustering, leading to a much narrower range of
as the shear strain rate varies. In the limit of vanishingly small
shear strain rate, we find a unique non-trivial value for the jamming density
that is independent of the initial system configuration. We conclude that shear
driven jamming is a unique and well defined critical point in the space of
shear driven steady states. We clarify the relation between glassy behavior,
rigidity and jamming in such systems and relate our results to recent
experiments.Comment: 10 pages, 11 figures, significantly expanded version as accepted for
publication in PR
Finite-Size-Scaling at the Jamming Transition: Corrections to Scaling and the Correlation Length Critical Exponent
We carry out a finite size scaling analysis of the jamming transition in
frictionless bi-disperse soft core disks in two dimensions. We consider two
different jamming protocols: (i) quench from random initial positions, and (ii)
quasistatic shearing. By considering the fraction of jammed states as a
function of packing fraction for systems with different numbers of particles,
we determine the spatial correlation length critical exponent ,
and show that corrections to scaling are crucial for analyzing the data. We
show that earlier numerical results yielding are due to the improper
neglect of these corrections.Comment: 5 pages, 4 figures -- slightly revised version as accepted for Phys.
Rev. E Rapid Communication
Jamming and Soft-Core Rheology
Many different physical systems, such as granular materials, colloids, foams and emulsions exhibit a jamming transition where the system changes from a liquid-like flowing state to a solid jammed state as the packing fraction increases. These systems are often modeled using soft-core particles with repulsive contact forces. In this thesis we explore several different dynamical models for these kinds of systems, and see how they affect the behavior around the jamming transition. We investigate the effect of different types of dissipative forces on the rheology, and study how different methods of preparing a particle configuration affect their probability to jam when quenched. We study the rheology of sheared systems close to the jamming transition. It has been proposed that the athermal jamming transition is controlled by a critical point, point J, with certain scaling properties. We investigate this using multivariable scaling analysis based on renormalization group theory to explore the scaling properties of the transition and determine the position of point J and some of the critical exponents