Observation of Backflow during the Anihilation of Topologocal Defects in Freely Suspended Smectic Films

Abstract

Freely suspended films in the smectic C phase are excellent templates for the study of topological defect dynamics. It is well known that, during the annihilation of a pair of disclinations with strengths +/−1, the +1 defect moves faster because it is carried towards its opponent by backflow, whereas the flow in the vicinity of the −1 defect is negligibly small. This backflow pattern is created by the defect motion itself. An experimental confirmation of this theoretical prediction and its quantitative characterization is achieved here by fluorescence labeling. Film regions near the defect positions are labeled and their displacements are tracked optically.

The structure of disintegrating defect clusters in smectic C freely suspended films

“…36 In experiments, flow generated in the annihilation process of defect pairs in freely suspended Smectic C films has been demonstrated using fluorescence microscopy and a photo-bleaching technique. 40 In the present cluster disintegration scenario, however, an experimental confirmation of backflow has not been tackled yet. Nevertheless, we hypothesize that near the positions of the outer +1 defects, the flow field is directed outward, with the defect motion, thus increasing the defect speed.…”

30 years of CNES parabolic flights for the benefit of the scientific community

“…Physics of matter: Research on board parabolic flights tries to investigate the structure of matter and its modification at macroscopic or microscopic scales. Physics of fluid [3][4][5][6], physics of granular media [7], test of principle of equivalence and atomic clocks [8], combustion [9,10]. .…”

Hydrodynamic Enhancement ofp-atic Defect Dynamics

“…While the biochemical aspects of these processes are mostly understood, less is known about the role of physical interactions. Their origin, nevertheless, can be singlehandedly ascribed to the existence of a hydrodynamic phenomenon known as backflow-the hydrodynamic flow resulting from spatial variations of the average microscopic orientation [33][34][35][36][37][38]. In passive liquid crystals, departure from the uniformly oriented equilibrium configuration is generally transient and often originates from a sudden change in the environmental conditions, such as the abrupt variation of an external electric or magnetic field in optical devices [39,40].…”