677 research outputs found
Kinetic theory of discontinuous shear thickening
A simple kinetic theory to exhibit a discontinuous shear thickening (DST) is
proposed. The model includes the collision integral and the friction from
environment as well as a thermostat term characterized by . The
viscosity of this model is proportional to for large shear rate
, while it is Newtonian for low . The emergence of the
DST is enhanced for lower density and lower nonzero .Comment: 4 pages, 2 figures, Powders and Grains 2017 (in press
Particle flows around an intruder
Particle flows injected as beams and scattered by an intruder are numerically
studied. We find a crossover of the drag force from Epstein's law to Newton's
law, depending on the ratio of the speed to the thermal speed. These laws can
be reproduced by a simple analysis of a collision model between the intruder
and particle flows. The crossover from Epstein's law to Stokes' law is also
found for the low-speed regime as the time evolution of the drag force caused
by beam particles. We also show the existence of turbulent-like behavior of the
particle flows behind the intruder with the aid of the second invariant of the
velocity gradient tensor and the relative mean square displacement for the
high-speed regime and a large intruder.Comment: 10 pages, 13 figure
Pattern dynamics of cohesive granular particles under a plane shear
We perform three dimensional molecular dynamics simulations of cohesive
granular particles under a plane shear. From the simulations, we found that the
granular temperature of the system abruptly decreases to zero after reaching
the critical temperature, where the characteristic time is
approximately represented by with the dissipation rate , the critical dissipation rate
and the exponent . We also found that there
exist a variety types of clusters depending on the initial density and the
dissipation rate.Comment: 4 pages, 5 figure
Kinetic theory for dilute cohesive granular gases with a square well potential
We develop the kinetic theory of dilute cohesive granular gases in which the
attractive part is described by a square well potential. We derive the
hydrodynamic equations from the kinetic theory with the microscopic expressions
for the dissipation rate and the transport coefficients. We check the validity
of our theory by performing the direct simulation Monte Carlo.Comment: 22 pages, 11 figure
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