Simulation study on inertial focusing of curved flexible filaments based on IB-LBM

This study investigates the inertial focusing behavior of curved filaments in straight microchannels to elucidate the individual effects of filament length, curvature, elasticity, and the channel Reynolds number (Re). Numerical simulations were performed using the immersed boundary-lattice Boltzmann method. The validity of the model was confirmed through grid independence tests and by comparing simulated inertial focusing of rigid particles with existing experimental benchmarks. Increasing filament length shifts the equilibrium position toward the channel centerline, broadens the focusing distribution, and prolongs the rotational period. Conversely, highly curved filaments focus farther from the centerline, exhibit a tighter focusing band, and rotate faster. Elasticity exerts a relatively minor influence, resulting only in a slight outward shift and marginal changes in the rotation period. Furthermore, higher Reynolds numbers—associated with steeper velocity gradients—drive focusing positions outward and compress the focusing interval, while simultaneously extending the rotational period. The inertial focusing of curved filaments is governed by the interplay of geometric configuration, mechanical properties, and flow conditions. These findings provide a theoretical basis for manipulating and separating curved particles in microfluidic systems.