  Two-dimensional simulations of the coarsening process of the
isotropic/smectic-A phase transition are presented using a high-order Landau-de
Gennes type free energy model. Defect annihilation laws for smectic
disclinations, elementary dislocations, and total dislocation content are
determined. The computed evolution of the orientational correlation length and
disclination density is found to be in agreement with previous experimental
observations showing that disclination interactions dominate the coarsening
process. The mechanism of smectic disclination movement, limited by the
absorption and emission of elementary dislocations, is found to be facilitated
by curvature walls connecting interacting disclinations. At intermediate times
in the coarsening process, split-core dislocation formation and interactions
displaying an effective disclination quadrupole configuration are observed.
This work provides the framework for further understanding of the formation and
dynamics of the diverse set of curvature defects observed in smectic liquid
crystals and other layered material systems.
