Electrohydrodynamic channeling effects in narrow fractures and pores

TL;DR

This study uses three-dimensional simulations to explore how electrohydrodynamic effects influence fluid flow in narrow fractures, revealing significant channeling alterations due to surface charge and electric double layers.

Contribution

It provides the first comprehensive 3D analysis of electrohydrodynamic flow in idealized fracture geometries, highlighting the impact of surface charge on flow channeling.

Findings

Flow channeling can be significantly increased by electrohydrodynamic effects.

Local flow in narrow regions can be slowed by up to 5%.

Electrohydrodynamics may influence transport and surface growth in geophysical systems.

Abstract

In low-permeability rock, fluid and mineral transport occur in pores and fracture apertures at the scale of micrometers and below. At this scale, the presence of surface charge, and a resultant electrical double layer, may considerably alter transport properties. However, due to the inherent non-linearity of the governing equations, numerical and theoretical studies of the coupling between electric double layers and flow have mostly been limited to two-dimensional or axisymmetric geometries. Here, we present comprehensive three-dimensional simulations of electrohydrodynamic flow in an idealized fracture geometry consisting of a sinusoidally undulated bottom surface and a flat top surface. We investigate the effects of varying the amplitude and the Debye length (relative to the fracture aperture) and quantify their impact on flow channeling. The results indicate that channeling can be significantly increased in the plane of flow. Local flow in the narrow regions can be slowed down by up to $5 \%$ compared to the same geometry without charge, for the highest amplitude considered. This indicates that electrohydrodynamics may have consequences for transport phenomena and surface growth in geophysical systems.