FIG. 6.
(Color online) Time sequential snapshots of the nematic director field n for nucleation (a) and annihilation (b) of defect pairs, where αaa = −2.0 and αpa = −0.6 are fixed. The (dimensionless) time spacing between frames is 5. (c) Polarity field associated with a motile +1/2 defect and an incipient crack on the bottom. (d) Relative speed of the two oppositely charged defects, as well as the mean flow speed near this defect pair, as a function of dimensionless time t′. In (a), (b), and (c), the color shows the scalar order parameter, plotted with the same scale as Fig. 5(b).