Multiscale Dynamics in Active Nematics

Active nematic liquid crystals exhibit chaotic dynamics powered by the motion of microscopic rod-like constituents. Using a microtubule-based active nematic, we measure the flow field both by labeling a small region of the fluid and by tracking the movement of individual filaments. Averaged flows are dipolar extensile with an ATP-dependent strain rate. The motion of individual microtubules is widely distributed about the average, which is modeled as an effective diffusion process. Our measurements pave the way for multiscale models of active nematics that connect the nanometer-scale motions of individual motors to the emergent dynamics, which takes place on scales of hundreds of microns and is described by a coarse-grained hydrodynamic framework.