The 10th Asian Symposium on Computational Heat Transfer and Fluid Flow ( ASCHT2025)

Electroosmotic flow (EOF) in polyelectrolyte (PE) solutions exhibits rich nonlinear behavior that deviates from classical electrokinetic theory. In this study, we report a nonlinear field-strength-dependent EOF transport in PE solutions confined within charged nanochannels. The EOF mobility μ_EOF arises not solely from increased driving force, but from hydrodynamic-shear-induced desorption of PE chains from the channel walls. This desorption reshapes the electric double layer (EDL), weakens charge inversion, and promotes more efficient transport through the channel center. Remarkably, under strong fields, systems with lower surface charge can exhibit higher EOF velocities than those with higher surface charge, revealing a nontrivial interplay between wall electrostatics and field-driven polymer migration. Parametric studies further demonstrate that surface charge density, chain length, and charge fraction collectively govern the onset and extent of the nonlinear response of μ_EOF to the applied electric field. This work offers a molecular-level insight into the origin of the nonlinear behavior of EOF in PE solutions, rooted in the coupling between polymer conformation, wall interactions, and EDL dynamics. These findings offer new insights into the design of tunable electrohydrodynamic transport in soft matter and nanoscale fluidic systems.

Electro-osmotic,molecular simulation,nonlinear electrokinetic,polyelectrolyte solution