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Velocity Effects on Dispersion in Porous Media With a Single Heterogeneity
Author(s) -
Cala Michael A.,
Greenkorn Robert A.
Publication year - 1986
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr022i006p00919
Subject(s) - porous medium , permeability (electromagnetism) , mechanics , dispersion (optics) , diffusion , materials science , displacement (psychology) , fick's laws of diffusion , convection , flow (mathematics) , flow velocity , porosity , fluid dynamics , thermodynamics , chemistry , optics , physics , composite material , psychology , biochemistry , membrane , psychotherapist
Regime changes during multifluid miscible displacement through a porous medium, containing a single heterogeneity were simulated. At very low fluid velocities (approximately 5 × 10 −5 cm/s), the displacement is predominantly controlled by diffusion. Increasing the fluid velocity causes inter pore convection to become a factor. The third regime is at even higher velocities (0.5 × 10 −3 to 5 ×10 3 cm/s) and is predominantly controlled by mechanical dispersion. Analysis of simulations for heterogeneous flow fields reveals a fourth regime where flow is governed by megascopic dispersion caused by heterogeneity. Flow in this regime appears to be non‐Fickian. A maximum Fickian velocity was determined for various parameters of the heterogeneous flow field. Permeability rato had the greatest effect on overall dispersivity. The greater the length ratio, the greater the overall dispersivity, and the greater the chance of the flow exhibiting non‐Fickian behavior. Changing the size ratio did not significantly change the overall dispersivity but did affect the megascopic regime occurrence.