Controllable particle migration in liquid crystal flows.

We observe novel positional control of a colloidal particle in microchannel flow of a nematic liquid crystal. Lattice Boltzmann simulations show multiple equilibrium particle positions, the existence and position of which are tunable using the driving pressure, in direct contrast to the classical Segré-Silberberg effect in isotropic liquids. In addition, particle migration in nematic flow occurs an order of magnitude faster. These new equilibria are determined through a balance of elastic forces, hydrodynamic lift and drag as well as order-flow interactions through the defect structure around the particle.