Spontaneous flows in active smectics with dislocations

We construct a hydrodynamic theory of active smectics A in two-dimensional space, including the creation/annihilation and motility of dislocations with Burgers’ number $\pm 1$. We derive analytical criteria on the set of parameters that lead to flows. We show that the motility of dislocations can lead to flow transitions with distinct features from the previously reported active Helfrich–Hurault shear instability with, notably, a first-order transition in the velocity from quiescence to turbulence.