113 research outputs found
Memory effect on the formation of drying cracks
We propose a model for the formation of drying cracks in a viscoplastic
material. In this model, we observe that when an external force is applied to a
viscoplastic material before drying, the material memorizes the effect of the
force as a plastic deformation. The formation of the drying cracks is
influenced by this plastic deformation. This outcome clarifies the result of a
recent experiments which demonstrated that a drying fracture pattern on a
powder-water mixture depends on the manner in which an external force is
applied before drying. We analytically express the position of the first crack
as a function of the strength of an external force applied before drying. From
the expression, we predict that there exists a threshold on the strength of the
force. When the force applied is smaller than the threshold, the first crack is
formed at the center of the mixture; however, when the force applied exceeds
the threshold, the position of the first crack deviates from the center. The
extent of the deviation increases as a linear function of the difference
between the strength of the force and the threshold.Comment: 9 pages, 9 figure
Nonequilibrium identities and response theory for dissipative particles
We derive some nonequilibrium identities such as the integral fluctuation
theorem and the Jarzynski equality starting from a nonequilibrium state for
dissipative classical systems. Thanks to the existence of the integral
fluctuation theorem we can naturally introduce an entropy-like quantity for
dissipative classical systems in far from equilibrium states.
We also derive the generalized Green-Kubo formula as a nonlinear response
theory for a steady dynamics around a nonequilibrium state. We numerically
verify the validity of the derived formulas for sheared frictionless granular
particles.Comment: 10 pages, 5 figures, to be published in Phys. Rev.
Rheology of sheared granular particles near jamming transition
We investigate the rheology of sheared granular materials near the jamming
transition point. We numerically determine the values of the critical fraction
and the exponents for the jamming transition using a finite size scaling and
the nonlinear minimization method known as the Levenberg-Marquardt algorithm.
The exponents are close to our previous theoretical prediction, but there is a
small discrepancy, if the critical point is independently determined.Comment: 10 pages, 4 figure
Mode-coupling theory of sheared dense granular liquids
Mode-coupling theory (MCT) of sheared dense granular liquids %in the vicinity
of jamming transition is formulated. Starting from the Liouville equation of
granular particles, the generalized Langevin equation is derived with the aid
of the projection operator technique. The MCT equation for the density
correlation function obtained from the generalized Langevin equation is almost
equivalent to MCT equation for elastic particles under the shear. It is found
that there should be the plateau in the density correlation function.Comment: 22 pages, 2 figure. to be published in Progress of Theoretical
Physics. to be published in Progress of Theoretical Physic
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