Surface anchoring mediates bifurcation in nematic microflows within cylindrical capillaries

Capillary microflows of liquid crystal phases are central to material, biological and bio-inspired systems. Despite their fundamental applied significance, a detailed understanding the stationary behavior nematic crystals (NLC-s) in cylindrical capillaries is still lacking. Here, using numerical simulations based on continuum theory Leslie, Ericksen, Parodi, we investigate NLC flows within possessing homeotropic (normal) uniform planar anchoring conditions. By considering material parameters flow-aligning NLC, 5CB, report that instead expected, unique director field monotonically approaching alignment angle over corresponding Ericksen numbers (dimensionless number capturing viscous vs elastic effects), second solution emerges at threshold flow rate (or pressure gradient). We demonstrate onset solution, nematodynamic bifurcation yielding distinct configurations gradient, can be controlled by surface driving mechanism (pressure-driven or volume-driven). For anchoring, this alternate orients against vicinity capillary center; while case, extends throughout volume, leading reduction speed with increasing gradients. While practical realization utilization such bifurcations await systematic exploration, signatures emergent rheology have been reported authors previously microfluidic environments, under both