role of annulus confinement on 2D active nematic behaviour

Defects play an important role in active-matter systems. They are nucleated because of the bend instability and in steady state are continuously created and annihilated. In this study we investigate a 2D active nematic confined in an annulus, which exhibits a rich dynamical behavior of the plus and minus half defects. The confinement effectively transforms the turbulent dynamics of the active nematic into coherent flow. We measure the positional-orientational distribution of defects in different confinements. We define three different states for the defects based on their positions and orientations, and calculate their transition rates.