title: Electro-osmosis of non-Newtonian fluids in porous media using lattice Poisson-Boltzmann method.
abstract: Electro-osmosis in porous media has many important applications in various areas such as oil and gas exploitation and biomedical detection. Very often, fluids relevant to these applications are non-Newtonian because of the shear-rate dependent viscosity. The purpose of this study was to investigate the behaviors and physical mechanism of electro-osmosis of non-Newtonian fluids in porous media. Model porous microstructures (granular, fibrous, and network) were created by a random generation-growth method. The nonlinear governing equations of electro-kinetic transport for a power-law fluid were solved by the lattice Poisson-Boltzmann method (LPBM). The model results indicate that: (i) the electro-osmosis of non-Newtonian fluids exhibits distinct nonlinear behaviors compared to that of Newtonian fluids; (ii) when the bulk ion concentration or zeta potential is high enough, shear-thinning fluids exhibit higher electro-osmotic permeability, while shear-thickening fluids lead to the higher electro-osmotic permeability for very low bulk ion concentration or zeta potential; (iii) the effect of the porous medium structure depends significantly on the constitutive parameters: for fluids with large constitutive coefficients strongly dependent on the power-law index, the network structure shows the highest electro-osmotic permeability while the granular structure exhibits the lowest permeability on the entire range of power law indices considered; when the dependence of the constitutive coefficient on the power law index is weaker, different behaviors can be observed especially in case of strong shear thinning.
authors.affiliation: Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084, China.
authors.forename: Simeng
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084, China.
authors.forename: Xinting
authors.initials: X
authors.lastname: He
authors.affiliation: School of Engineering, University of Liverpool, Liverpool L69 3GH, UK.
authors.forename: Volfango
authors.initials: V
authors.lastname: Bertola
authors.affiliation: Department of Engineering Mechanics and CNMM, Tsinghua University, Beijing 100084, China. Electronic address: mrwang@tsinghua.edu.cn.
authors.forename: Moran
authors.initials: M
authors.lastname: Wang
mesh_terms: D055664:Electrochemical Techniques / Q000379:methods*; D007700:Kinetics; D008962:Models, Theoretical; D009995:Osmosis; D012212:Rheology
keywords: Electro-osmosis; Lattice Poisson–Boltzmann method; Non-Newtonian fluid; Porous media