Pore-scale dispersion: Bridging the gap between microscopic pore structure and the emerging macroscopic transport...

Area of Science:

• Geosciences
• Environmental Science
• Chemical Engineering

Background:

• Understanding solute transport in porous media is crucial for environmental remediation and resource management.
• Advection-dominated dispersion (high Péclet number) presents unique challenges in modeling transport behavior.
• Natural porous media, such as carbonates, exhibit complex pore structures influencing dispersion.

Purpose of the Study:

• To develop an efficient and universal statistical methodology for describing advection-dominated dispersion.
• To investigate the relationship between pore-scale characteristics and macroscopic transport behavior.
• To establish a model that accurately predicts tracer particle dispersion in natural porous media.

Main Methods:

• Direct numerical simulation (DNS) of tracer particle dispersion.
• Analysis of the influence of tortuosity on transverse dispersion.
• Characterization of spatial variability using Lagrangian velocity correlation length.
• Development of a statistical transport model linking pore-scale to macro-scale behavior.

Main Results:

• Transverse dispersion is primarily governed by tortuosity and approaches a Fickian limit.
• Longitudinal dispersion is Fickian in bead packs but superdiffusive in other natural media.
• Lagrangian velocity correlation length effectively characterizes spatial transport variability.
• The developed statistical model accurately reproduces longitudinal transport and transverse Fickian limits.

Conclusions:

• A computationally efficient methodology for universal statistical description of advection-dominated dispersion is presented.
• The model successfully connects pore-scale properties to macroscopic transport phenomena.
• The findings provide insights into solute transport dynamics in diverse natural porous media.