Nonuniqueness of hydrodynamic dispersion revealed using fast 4D synchrotron x-ray imaging.

Autor:	Chen Y; Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK., Steeb H; Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany., Erfani H; Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK., Karadimitriou NK; Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany., Walczak MS; Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK., Ruf M; Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany., Lee D; Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany., An S; Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK., Hasan S; School of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia., Connolley T; Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK., Vo NT; Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK., Niasar V; Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK.
Jazyk:	angličtina
Zdroj:	Science advances [Sci Adv] 2021 Dec 24; Vol. 7 (52), pp. eabj0960. Date of Electronic Publication: 2021 Dec 22.
DOI:	10.1126/sciadv.abj0960
Abstrakt:	Experimental and field studies reported a significant discrepancy between the cleanup and contamination time scales, while its cause is not yet addressed. Using high-resolution fast synchrotron x-ray computed tomography, we characterized the solute transport in a fully saturated sand packing for both contamination and cleanup processes at similar hydrodynamic conditions. The discrepancy in the time scales has been demonstrated by the nonuniqueness of hydrodynamic dispersion coefficient versus injection rate (Péclet number). Observations show that in the mixed advection-diffusion regime, the hydrodynamic dispersion coefficient of cleanup is significantly larger than that of the contamination process. This nonuniqueness has been attributed to the concentration-dependent diffusion coefficient during the cocurrent and countercurrent advection and diffusion, present in contamination and cleanup processes. The new findings enhance our fundamental understanding of transport processes and improve our capability to estimate the transport time scales of chemicals or pollution in geological and engineering systems.
Databáze:	MEDLINE
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