Numerical investigation of rotating induced-charge electro-osmotic flow around an eccentric cylinder using the Giesekus model

Induced-charge electro-osmotic flow (ICEOF) plays a pivotal role in microfluidic mixing by generating nonlinear convective vortices. However, the coupling mechanisms between rotating ICEOF (ROT-ICEOF) and the viscoelasticity of practical biological samples remain largely unexplored. This study numerically investigates the flow characteristics of Giesekus viscoelastic fluids around a polarizable cylinder under the influence of a rotating electric field. To ensure numerical stability, potential decomposition and the log-conformation tensor formulation were adopted. We systematically analyzed the effects of polymer concentration, mobility factor, electric field parameters, and electrode eccentricity on fluid flow. The results reveal that the inherent “energy storage and release” mechanism of viscoelastic fluids creates an asymmetric flow velocity envelope, fundamentally distinguishing it from Newtonian flows. Crucially, the peak flow velocity exhibits a non-monotonic dependence on polymer concentration, revealing an intense dynamic competition between viscous dissipation and a microscopic “elastic pumping” effect. Moreover, the critical concentration corresponding to this velocity rebound shifts to lower values under higher electric field strengths. Conversely, increasing the mobility factor enhances fluid flow through the shear-thinning effect. The intensity of fluid flow exhibits a non-monotonic dependence on the electric field frequency, peaking at 100 Hz due to dynamic competition between viscoelastic relaxation and induced double-layer charging. Furthermore, excessively high electric field amplitudes trigger a reduction in local apparent viscosity, causing the fluid velocity to surpass the traditional quadratic scaling law. Additionally, the study identifies an optimal electrode eccentricity ( ε = 0.513) that maximizes electro-osmotic driving force by exploiting spatial asymmetry; conversely, excessive eccentricity suppresses fluid flow due to the reverse polarization effects. This study elucidates the intricate coupling mechanisms between viscoelasticity and electrodynamics, providing a theoretical foundation for the design of highly efficient microfluidic mixers.