207 research outputs found
Reply to: Comment on `Long-range electrostatic interactions between like-charged colloids: steric and confinement effects'
In his Comment (cond-mat/0104060) to [Phys. Rev. E 60, 6530 (1999)], Mateescu
shows that while the effective interactions remain repulsive when the specific
size of the micro-ions is taken into account via a Modified Poisson-Boltzmann
equation, a similar conclusion cannot be reached for the situation of complete
lateral confinement. This point is correct but has already been considered in a
more general study [Phys. Rev. E 62, R1465 (2000), where repulsion is
generically obtained]; moreover, we argue that it illustrates the irrelevancy
of the notion of pair potential in completely confined configurations, as shown
on a simple example
Kovacs-like memory effect in driven granular gases
While memory effects have been reported for dense enough disordered systems
such as glasses, we show here by a combination of analytical and simulation
techniques that they are also intrinsic to the dynamics of dilute granular
gases. By means of a certain driving protocol, we prepare the gas in a state
where the granular temperature coincides with its long time limit. However,
does not subsequently remain constant, but exhibits a non-monotonic
evolution before reaching its non-equilibrium steady value. The corresponding
so-called Kovacs hump displays a normal behavior for weak dissipation (as
observed in molecular systems), but is reversed under strong dissipation, where
it thus becomes anomalous.Comment: 5 pages, to appear in Physical Review Letter
Free cooling and inelastic collapse of granular gases in high dimensions
The connection between granular gases and sticky gases has recently been
considered, leading to the conjecture that inelastic collapse is avoided for
space dimensions higher than 4. We report Molecular Dynamics simulations of
hard inelastic spheres in dimensions 4, 5 and 6. The evolution of the granular
medium is monitored throughout the cooling process. The behaviour is found to
be very similar to that of a two-dimensional system, with a shearing-like
instability of the velocity field and inelastic collapse when collisions are
inelastic enough, showing that the connection with sticky gases needs to be
revised.Comment: 6 pages, 6 figures (7 postscript files), submitted to EPJ
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