12 research outputs found
Diffusion-controlled death of -particle and -particle islands at propagation of the sharp annihilation front
We consider the problem of diffusion-controlled evolution of the system
-particle island - -particle island at propagation of the sharp
annihilation front . We show that this general problem, which
includes as particular cases the sea-sea and the island-sea problems,
demonstrates rich dynamical behavior from self-accelerating collapse of one of
the islands to synchronous exponential relaxation of the both islands. We find
a universal asymptotic regime of the sharp front propagation and reveal limits
of its applicability for the cases of mean-field and fluctuation fronts.Comment: 4 revtex pages, 1 jpg figure. Submitted to Phys. Rev.
Diffusion-controlled annihilation : The growth of an particle island from a localized -source in the particle sea
We present the growth dynamics of an island of particles injected from a
localized -source into the sea of particles and dying in the course of
diffusion-controlled annihilation . We show that in the 1d case the
island unlimitedly grows at any source strength , and the dynamics of
its growth {\it does not depend} asymptotically on the diffusivity of
particles. In the 3d case the island grows only at ,
achieving asymptotically a stationary state ({\it static island}). In the
marginal 2d case the island unlimitedly grows at any but at the time of its formation becomes exponentially large. For all
the cases the numbers of surviving and dying particles are calculated, and
the scaling of the reaction zone is derived.Comment: 5 REVTEX pages, no figure
Diffusion-controlled annihilation with initially separated reactants: The death of an particle island in the particle sea
We consider the diffusion-controlled annihilation dynamics with
equal species diffusivities in the system where an island of particles is
surrounded by the uniform sea of particles . We show that once the initial
number of particles in the island is large enough, then at any system's
dimensionality the death of the majority of particles occurs in the {\it
universal scaling regime} within which of the particles die at
the island expansion stage and the remaining at the stage of its
subsequent contraction. In the quasistatic approximation the scaling of the
reaction zone has been obtained for the cases of mean-field ()
and fluctuation () dynamics of the front.Comment: 4 RevTex pages, 1 PNG figure and 1 EPS figur
Catastrophe in diffusion-controlled annihilation dynamics: general scaling properties
We present a systematic analytical and numerical study of the annihilation catastrophe
phenomenon which develops in an open system, where species A and B diffuse from the bulk of
restricted medium and die on its surface (desorb) by the reaction A + B → 0.
This phenomenon arises in the diffusion-controlled limit as a result of self-organizing
explosive growth (drop) of the surface concentrations of, respectively, slow and fast
particles (concentration explosion) and manifests itself in the form of an abrupt singular
jump of the desorption flux relaxation rate. In the recent work [B.M. Shipilevsky, Phys.
Rev. E 76, 031126 (2007)] a closed scaling theory of catastrophe development
has been given for the asymptotic limit when the characteristic time scale of explosion
becomes much less than the characteristic time scales of diffusion of slow and fast
particles at an arbitrary ratio of their diffusivities 0
<p<
1. In this paper we consider the behavior of the system at strong
difference of species diffusivities p ≪ 1 and reveal a rich general pattern of
catastrophe development for an arbitrary ratio of the characteristic time scales of
explosion and fast particle diffusion. As striking results we find remarkable scaling
properties of catastrophe evolution at the crossover between two limiting regimes with
radically different dynamics