2016/08/31 by Diana Khoromskaia, Gareth P. Alexander · 46 citations
Engineering · Materials Science · Physics and Astronomy · #Advanced Materials and Mechanics #Antipodal point #Classical mechanics #Condensed matter physics #Deformation (meteorology) #Dynamics (music) #Field (mathematics) #Flow (mathematics) #Geometry #Liquid crystal #Mechanics #Micro and Nano Robotics #Physics #Pickering emulsions and particle stabilization #Planar #Shell (structure) #Topological defect #Vortex #cond-mat.soft
paper · pdf · doi:10.1088/1367-2630/aa89aa
published in New Journal of Physics 19(10), 103043 (IOP Publishing) · 10 pages, 6 figures
openalex created_date 2016/10/07 · arxiv created 2017/01/27 · openalex publication_date 2017/09/01 · arxiv updated 2017/11/13 · openalex updated_date 2026/08/06
We present a hydrodynamic model for a thin spherical shell of active nematic liquid crystal with an arbitrary configuration of defects. The active flows generated by defects in the director lead to the formation of stable vortices, analogous to those seen in confined systems in flat geometries, which generate effective dynamics for four +1/2 defects that reproduces the tetrahedral to planar oscillations observed in experiments. As the activity is increased and two counterrotating vortices dominate the flow, the defects are drawn more tightly into pairs, rotating about antipodal points. We extend this situation to also describe the dynamics of other configurations of defects. For example, two +1 defects are found to attract or repel according to the local geometric character of the director field around them and the extensile or contractile nature of the material, while additional pairs of opposite charge defects can give rise to flow states containing more than two vortices. Finally, we describe the generic relationship between defects in the orientation and singular points of the flow, and suggest implications for the three-dimensional nature of the flow and deformation in the shape of the shell.