Spatial Fluctuations Of Fluid Velocities In Flow Through A Three-Dimensional Porous Medium

TL;DR

This study visualizes and analyzes the spatial fluctuations of fluid velocities in a 3D porous medium, revealing exponential distributions and pore-scale correlations influenced by the medium's geometry.

Contribution

It provides direct visualization and quantification of flow fluctuations and correlations in 3D porous media, highlighting non-random flow behavior despite complex pore structures.

Findings

Velocity magnitudes are exponentially distributed.

Flow components show exponential distribution.

Flow correlations are determined by pore geometry.

Abstract

We use confocal microscopy to directly visualize the spatial fluctuations in fluid flow through a three-dimensional porous medium. We find that the velocity magnitudes and the velocity components both along and transverse to the imposed flow direction are exponentially distributed, even with residual trapping of a second immiscible fluid. Moreover, we find pore-scale correlations in the flow that are determined by the geometry of the medium. Our results suggest that, despite the considerable complexity of the pore space, fluid flow through it is not completely random.