Long- and Short-Range Interactions of Defects in Anisotropic Hydrodynamical Systems

The experimental data on the mutual interaction of a pair of topological defects in the roll pattern of electroconvecting nematics at a very small or negligible external stress are presented. It is shown that the mutual interaction of defects in a pair becomes significant only below a characteristic length, which is universal for both climbing and gliding and about an order of magnitude larger than the corresponding coherence length.