Numerical study of the influence of the electrokinetic effect on the growth of an oxide film at the pore scale

• Main Authors: Grigoriev, Vasiliy V., Savvin, Anton V.
• Format: Conference Proceeding
• Language: English
• Subjects: Boundary conditions; Electric fields; Electrokinetic effects; Electrokinetics; Electroosmosis; Enhanced oil recovery; Film thickness; Finite element method; Flow paths; Kinetics; Liquid-solid interfaces; Oxidation; Oxide coatings; Oxidizing agents; Porous materials; Porous media; Reaction kinetics; Scale (corrosion); Soil permeability; Soil remediation
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0106444

Electrokinetic effects in porous media play a key role in a number of natural and industrial processes. Applications such as enhanced oil recovery, soil remediation, and even drug delivery are influenced by the Coulomb forces generated by solid-liquid interfacial interactions. These electrokinetic effects promote the development of an inhomogeneous sliding flow over charged surfaces at the pore scale, which can have a significant effect on the hydrodynamics of dense porous materials. For the transfer of ionic solutions in such systems, a combined effect of hydrodynamic transfer and electrokinetic transfer can be expected. While pressure driven transport will be expressed in high permeability flow paths, electric field transport will be more pronounced in dense pores where the electrical diffuse layer is not negligible. To predict the growth of an oxide film, a model is used that includes both linear kinetics and classical parabolic oxidation kinetics. It is based on the quasi-stationary approximation for a thin oxide film. The local film thickness is considered a desired value, which, in particular, is explicitly included in the boundary condition for the concentration of the oxidant. Various mechanisms of flow movement were considered, for example, conventional pressure controlled flow, pure electroosmosis, as well as their superposition. Next, the effect of these different flow regimes on oxidant transfer and pore-scale oxide growth was analyzed. The numerical solution of the two-dimensional problem was obtained by the finite element method using the FEniCS computing platform.