Anisotropic velocity statistics of topological defects under shear flow

摘要

We report numerical results on the velocity statistics of topological defectsduring the dynamics of phase ordering and non-relaxational evolution assistedby an external shear ow. We propose a numerically efficient tracking method forfinding the position and velocity of defects, and apply it to vortices in auniform field and dislocations in anisotropic stripe patterns. Duringrelaxational dynamics, the distribution function of the velocity fuctuations ischaracterized by a dynamical scaling with a scaling function that has a robustalgebraic tail with an inverse cube power law. This is characteristic todefects of codimension two, e.g. point defects in two dimensions and filamentsin three dimensions, regardless of whether the motion is isotropic (as forvortices) or highly anisotropic (as for dislocations). However, the anisotropicdislocation motion leads to anisotropic statistical properties when theinteraction between defects and their motion is in infuenced by the presence ofan external shear flow transverse to the stripe orientation.