Influence of viscoelastic properties on induced charge electro-osmosis of Phan–Thien–Tanner fluids around a metal cylinder

Abstract

Efficient mixing of chemicals is a key issue in microfluidics because of the limitations of low diffusivity in laminar flow. Induced charge electro-osmosis (ICEO), which generates quadrupole vortices, has been shown to be a simple and effective method for rapid mixing. The aim of this work is to improve the mixing of viscoelastic fluids using ICEO, thus extending the application of microfluidics in biomedical and chemical analysis. A simplified Phan–Thien–Tanner (sPTT) constitutive model was used to characterize the flow properties of the viscoelastic fluid, and the Navier-Stokes (NS) and Poisson-Nernst-Planck (PNP) equations were used to control the potential and ion concentration distributions, respectively. Numerical simulations of ICEO around a polarized cylinder in a two-dimensional cavity filled with an electrolyte solution have been carried out using the finite volume method. The effects of Weissenberg number (Wi), viscosity ratio (β), and extensibility parameter (ε) on the velocity and flow field were investigated. The results show that the larger ε and Wi are, the larger the maximum velocity is, and the peak velocity increases with increasing ε and Wi. When ε increases from 0.01 to 0.8, the peak velocity increases from 23.22 × 10⁻⁴ to 31.73 × 10⁻⁴. The maximum velocity at Wi = 10 is about twice that at Wi = 0.01.