  When a nematic liquid crystal is confined in a porous medium with strong
anchoring conditions, topological defects, called disclinations, are stably
formed with numerous possible configurations. Since the energy barriers between
them are large enough, the system shows multistability. Our lattice Boltzmann
simulations demonstrate dynamic couplings between the multistable defect
pattern and the flow in a regular porous matrix. At sufficiently low flow
speed, the topological defects are pinned at the quiescent positions. As the
flow speed is increased, the defects show cyclic motions and nonlinear
rheological properties, which depend on whether or not they are topologically
constrained in the porous networks. In addition, we discovered that the defect
pattern can be controlled by controlling the flow. Thus, the flow path is
recorded in the porous channels owing to the multistability of the defect
patterns.
