2023/11/15 by Siamak Mirfendereski, Mirfendereski, Siamak, Jae Sung Park +1
Chemical Engineering · Chemistry · Materials Science · #Electrostatics and Colloid Interactions #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Material Dynamics and Properties #Rheology and Fluid Dynamics Studies #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.2311.09121
openalex publication_date 2023/11/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The rheological behaviour of dense suspensions of ideally conductive particles in the presence of both electric field and shear flow is studied using large-scale numerical simulations. Under the action of an electric field, these particles are known to undergo dipolophoresis, which is the combination of two nonlinear electrokinetic phenomena -- induced-charge electrophoresis and dielectrophoresis. For ideally conductive particles, induced-charge electrophoresis is predominant over dielectrophoresis, resulting in transient pairing dynamics. The shear viscosity and first and second normal stress differences N1 and N2 of such suspensions are examined over a range of volume fractions 15% \leqslant ϕ\leqslant 50% as a function of Mason number Mn, which measures the relative importance of viscous shear stress over electrokinetic-driven stress. For Mn < 1 or low shear rates, the dipolophoresis is shown to dominate the dynamics, resulting in a relatively low-viscosity state. The positive N1 and negative N2 are observed at ϕ< 30%, which is similar to Brownian suspensions, while their signs are reversed at ϕ≥ 30%. For Mn ≥ 1, the shear thickening starts to arise at ϕ≥ 30%, and an almost five-fold increase in viscosity occurs at ϕ= 50%. Both N1 and N2 are negative for Mn ≫ 1 at all volume fractions considered. We illuminate the transition in rheological behaviours from dipolophoresis to shear dominance around Mn = 1 in connection to suspension microstructure and dynamics. Lastly, our findings reveal the potential use of nonlinear electrokinetics as a means of active rheology control for such suspensions.