Diffusion-controlled formation and collapse of a d-dimensional A-particle island in the B-particle sea

Abstract

We consider diffusion-controlled evolution of a $d$-dimensional $A$-particle island in the $B$-particle sea at propagation of the sharp reaction front $A+B\to 0$ at equal species diffusivities. The $A$-particle island is formed by a localized (point)$A$-source with a strength $\lambda$ that acts for a finite time $T$. We reveal the conditions under which the island collapse time $t_c$ becomes much longer than the injection period $T$ (long-living island) and demonstrate that regardless of $d$ the evolution of the long-living island radius $r_f(t)$ is described by the universal law ${\zeta }_f=r_f/r_f^M=\sqrt{e\tau |\ln \tau |}$ where $\tau =t/t_c$ and $r_f^M$ is the maximal island expansion radius at the front turning point $t_M=t_c/e$. We find that in the long-living island regime the ratio $t_c/T$ changes with the increase of the injection period $T$ by the law $\propto ({\lambda }^2{T}^{2-d}{)}^{1/d}$ i.e. increases with the increase of $T$ in the one-dimensional (1D) case, does not change with the increase of $T$ in the 2D case and decreases with the increase of $T$ in the 3D case. We derive the scaling laws for particles death in the long-living island and determine the limits of their applicability. We demonstrate also that these laws describe asymptotically the evolution of the $d$-dimensional spherical island with a uniform initial particle distribution generalizing the results obtained earlier for the quasi-one-dimensional geometry. As striking results we present a systematic analysis of the front relative width evolution for fluctuation, logarithmically modified and mean-field regimes and demonstrate that in a wide range of parameters the front remains sharp up to a narrow vicinity of the collapse point.

14 pages, 4 figures

References in corpus (2)

• Complex motion of precipitation bands
• Diffusion-controlled death of $A$-particle and $B$-particle islands at propagation of the sharp annihilation front $A+B\to 0$

Cited by in corpus (1)

• Diffusion-controlled coalescence, fragmentation and collapse of $d$-dimensional $A$-particle islands in the $B$-particle sea