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Pore‐scale intermittent velocity structure underpinning anomalous transport through 3‐D porous media
Author(s) -
Kang Peter K.,
Anna Pietro,
Nunes Joao P.,
Bijeljic Branko,
Blunt Martin J.,
Juanes Ruben
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061475
Subject(s) - streamlines, streaklines, and pathlines , porous medium , vector field , mechanics , flow velocity , porosity , scale (ratio) , geology , particle (ecology) , flow (mathematics) , physics , geophysics , geotechnical engineering , oceanography , quantum mechanics
We study the nature of non‐Fickian particle transport in 3‐D porous media by simulating fluid flow in the intricate pore space of real rock. We solve the full Navier‐Stokes equations at the same resolution as the 3‐D micro‐CT (computed tomography) image of the rock sample and simulate particle transport along the streamlines of the velocity field. We find that transport at the pore scale is markedly anomalous: longitudinal spreading is superdiffusive, while transverse spreading is subdiffusive. We demonstrate that this anomalous behavior originates from the intermittent structure of the velocity field at the pore scale, which in turn emanates from the interplay between velocity heterogeneity and velocity correlation. Finally, we propose a continuous time random walk model that honors this intermittent structure at the pore scale and captures the anomalous 3‐D transport behavior at the macroscale.