Measurement and analysis of non-Fickian dispersion in heterogeneous porous media

Levy, Melissa; Berkowitz, Brian

doi:10.1016/s0169-7722(02)00204-8

Cited by 347 publications

(329 citation statements)

References 28 publications

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“…Variability in the conductivities between the capped and unconfined cases can be attributed to two factors: (1) variation in packing between the two flow cells in which the sand was less consolidated in the unconfined system, and (2) clay dispersion into pore space of the sand in the capped case, thereby reducing the saturated conductivity. The 31% decrease between the saturated conductivity in the unconfined and capped systems is within the range observed in similar laboratory flow-cell experiments [Levy and Berkowitz, 2003;Conrad et al, 2002;Schroth et al, 1996].…”

Section: Unconfined Systemsupporting

confidence: 83%

“…These sands consist of quartz with minimal surface coatings (99.8% pure SiO 2 , as reported by UNIMIN). Three grain sizes were used in this study, with properties shown in Table 1 [Levy and Berkowitz, 2003;Conrad et al, 2002;Schroth et al, 1996].…”

Section: Setupmentioning

confidence: 99%

“…The 3.0-cm-long blocks were packed in 1.5-cm layers using 1-mm metal dividers to establish sharp contacts between regions of different sands and removed as packing progressed. The random heterogeneous structure is discussed by Levy and Berkowitz [2003]. Photographs of all three systems are shown later.…”

Section: Setupmentioning

confidence: 99%

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Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Dror

Berkowitz

Gorelick

2004

Water Resources Research

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[1] The effects of air injection on flow through porous media were explored in a series of 1-m and 2-m laboratory flow cells. Our motivation was to examine air barriers as an alternative to hydraulic barriers to inhibit saline intrusion in coastal areas. Steady flow conditions were created in homogeneous and heterogeneous unconsolidated sand systems. Dry air was injected at progressively higher flow rates through a well in the center of each flow cell. Discharge and NaClÀtracer breakthrough data were measured at the outflow reservoir of each cell. In addition, a dye tracer was used to visualize the flow patterns. In all cases, air injection was found to produce stable, low-conductivity barriers that reduced discharge by an order of magnitude or more. Effective hydraulic conductivity values determined from discharge and hydraulic head data showed exponential declines with increased air-injection rates in all cases. Numerical simulation was used to quantify hydraulic conductivity and effective porosity values in the saturated and aerated regions created by air injection, and to study advective flow behavior. Pore-filling cement formed in the air-injection region and was analyzed to determine its composition, mass, and volume. Approximately 60% of the cement consisted of soluble minerals, and 40% was less soluble carbonates. Evaporation and increase in solution pH due to stripping of CO 2 by the injected air were responsible for creating the cement. The cement occupied <10% of the pore space in the sand-cement aggregate. Both the air and mineral pore-fillings dissolved when air injection ceased, indicating that both barriers are temporary. These results serve as a preliminary proof of concept that air-injection barriers might effectively inhibit undesired subsurface flow, such as saline intrusion or contaminated groundwater.

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Section: Unconfined Systemsupporting

confidence: 83%

Section: Setupmentioning

confidence: 99%

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Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Dror

Berkowitz

Gorelick

2004

Water Resources Research

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“…Continuous time random walk (CTRW) [Montroll and Weiss, 1965;Scher and Lax, 1973;Berkowitz et al, 2000] also has the potential to model a range of transport behaviors. CTRW models transport as a series of particle jumps, with particle migration coupled in space and time Levy and Berkowitz, 2003]. The principal characteristics of the migration of a tracer are dominated by the late time behavior of the joint probability function ψ(s, t), the probability rate for a displacement s with difference of arrival times t .…”

Section: W07402mentioning

confidence: 99%

“…Particle migration is coupled in time and space, accounting for particle transitions that extend over short and long distances, and short and long times [Margolin and Berkowitz, 2000;Levy and Berkowitz, 2003]. The joint probability density function ψ(s, t) describes each particle transition over a distance and direction s in time t, with a power law tail for ψ(s, t) at large time .…”

Section: Ctrwmentioning

confidence: 99%

Non‐Fickian transport in homogeneous unsaturated repacked sand

Bromly

Hinz

2004

Water Resources Research

136

108

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[1] It is commonly assumed a priori that solute transport experiments conducted in homogeneously repacked laboratory columns can be described by the advective-dispersive (AD) or single-rate mobile-immobile (MIM) transport model. To investigate this, nonreactive transport through macroscopically homogeneous repacked unsaturated sand was studied at two water contents using laboratory columns of diameter of 11 cm and lengths of 10, 20, and 40 cm. Non-Fickian behavior was found to dominate transport at this scale, with long breakthrough curve (BTC) tailing persistent over the range of column lengths tested. Measured BTC tails were well described by the single-rate MIM model at each depth; however, over the range of travel distances studied BTC tailing was better explained as a result of stochastic-convective (SC) transport or continuous time random walk (CTRW). The SC model was applied using the BTC measured at 10 cm as the probability density function to make predictions to subsequent depths. The CTRW model spreading parameter (b) remained approximately constant across the range of both travel distances and water contents considered. It is concluded that the assumption of a single-rate MIM model cannot be made a priori for macroscopically homogeneous unsaturated sands. In this case, variability between replicates prevented identification of whether a SC transfer function or CTRW provided the best description of transport. These results demonstrate the variability in transport as a result of heterogeneities in column packing, even for macroscopically homogeneous sand, and emphasize the importance of studying transport over a range of travel distances in order to allow prediction of transport.

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On the Fundamentals of Hydrological Sciences

Blöschl

2005

Encyclopedia of Hydrological Sciences

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Although there is no universal theory in hydrology that starts from first principles, the various branches of hydrology show numerous common threads. They relate to the nature of the processes including their space–time variability, the general principles of hydrological measurements, and the types of methods for representing hydrological processes in a quantitative way, either statistically or deterministically. The purpose of this article is to provide some common ground for this Encyclopedia to highlight the particularities of the hydrological sciences.

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Measurement and analysis of non-Fickian dispersion in heterogeneous porous media

Cited by 347 publications

References 28 publications

Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Effects of air injection on flow through porous media: Observations and analyses of laboratory‐scale processes

Non‐Fickian transport in homogeneous unsaturated repacked sand

On the Fundamentals of Hydrological Sciences

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