  The selective entrapment of mutually annihilating species within a
phase-changing carrier fluid is explored by both analytical and numerical
means. The model takes full account of the dynamic heterogeneity which arises
as a result of the coupling between hydrodynamic transport, dynamic
phase-transitions and chemical reactions between the participating species, in
the presence of a selective droplet interface. Special attention is paid to the
dynamic symmetry breaking between the mass of the two species entrapped within
the expanding droplet as a function of time. It is found that selective sources
are much more effective symmetry breakers than selective diffusion. The present
study may be of interest for a broad variety of advection-diffusion-reaction
phenomena with selective fluid interfaces, including the problem of electroweak
baryogenesis.
