Pore‐scale intermittent velocity structure underpinning anomalous transport through 3‐D porous media

Kang, Peter K.; Anna, Pietro de; Nunes, J.P. Pereira; Bijeljic, Branko; Blunt, Martin J.; Juanes, Rubén

doi:10.1002/2014gl061475

Cited by 153 publications

(232 citation statements)

References 43 publications

(54 reference statements)

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“…The resulting flow fields provide valuable data to study the microscopic transport process in detail. Furthermore, this data gives important guidance for the development of effective models that can be applied to simulate flow and transport at scales larger than the pore scale [19,20]. For example, Kang et al [19] studied the advection-dominated dispersion in Berea sandstone based on a flow field stemming from micro-CT scanning and pore-scale DNS.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, this data gives important guidance for the development of effective models that can be applied to simulate flow and transport at scales larger than the pore scale [19,20]. For example, Kang et al [19] studied the advection-dominated dispersion in Berea sandstone based on a flow field stemming from micro-CT scanning and pore-scale DNS. They found that the dispersion in longitudinal direction is superdiffusive, with the variance of tracer particle positions scaling with time to the power of 1.5.…”

Section: Introductionmentioning

confidence: 99%

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

Meyer

Bijeljic

2016

Phys. Rev. E

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We devise an efficient methodology to provide a universal statistical description of advectiondominated dispersion (Péclet → ∞) in natural porous media including carbonates. Firstly, we investigate the dispersion of tracer particles by direct numerical simulation (DNS). The transverse dispersion is found to be essentially determined by the tortuosity and it approaches a Fickian limit within a dozen characteristic scales. Longitudinal dispersion was found to be Fickian in the limit for bead packs and superdiffusive for all other natural media inspected. We demonstrate that the Lagrangian velocity correlation length is a quantity that characterizes the spatial variability for transport. Finally, a statistical transport model is presented that sheds light on the connection between pore-scale characteristics and the resulting macroscopic transport behavior. Our computationally efficient model accurately reproduces the transport behavior in longitudinal direction and approaches the Fickian limit in transverse direction. *

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Meyer

Bijeljic

2016

Phys. Rev. E

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“…In the three dimensions, it was found [3] that the transverse velocity autocorrelation decays faster, though the absolute value is strongly correlated in time, a feature also observed in turbulent flows [5]. These remarkable properties have led to the suggestion that the Lagrangian particle velocities is given by a Markov process in space (at equidistant positions along the Lagrangian trajectories) and not in time [6,7].…”

Section: Introductionmentioning

confidence: 97%

“…In a Markov process the particle motion can be seen as a correlated continuous time random walk (CTRW). Using a correlated CTRW, several signatures of anomalous transport behavior were accurately reproduced such as the long tails of the first passage time distribution [6], the non-linear scaling of the second centered moment of the particles longitudinal and transverse displacements [3,6,8], the probability distribution function of the Lagrangian velocity increments for different time lags among others [1].…”

Section: Introductionmentioning

confidence: 98%

“…Particles passively advected by the flow in the pore-space, so-called Lagrangian particles, follow trajectories with periods of almost stagnation punctuated by bursts of fast fluctuating motion [1][2][3]. In a Berea sandstone sample, it was shown by a three dimensional simulation that this intermittent behavior was equally significant in both longitudinal (the mean flow direction) and transverse directions [3]. The chaotic Lagrangian dynamic emerges despite the fact that the inertia of the fluid is negligible in many natural and industrial settings, i.e., the flow happens at low Reynolds numbers.…”

Section: Introductionmentioning

confidence: 99%

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Simulating anomalous dispersion in porous media using the unstructured lattice Boltzmann method

et al. 2015

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Flow in porous media is a significant challenge to many computational fluid dynamics methods because of the complex boundaries separating pore fluid and host medium. However, the rapid development of the lattice Boltzmann methods and experimental imaging techniques now allow us to efficiently and robustly simulate flows in the pore space of porous rocks. Here we study the flow and dispersion in the pore space of limestone samples using the unstructured, characteristic based off-lattice Boltzmann method. We use the method to investigate the anomalous dispersion of particles in the pore space. We further show that the complex pore network limits the effectivity by which pollutants in the pore space can be removed by continuous flushing. In the smallest pores, diffusive transport dominates over advective transport and therefore cycles of flushing and no flushing, respectively, might be a more efficient strategy for pollutant removal.

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Impact of velocity correlation and distribution on transport in fractured media: Field evidence and theoretical model

Kang

Borgne

Dentz

et al. 2015

Water Resources Research

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176

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Flow and transport through fractured geologic media often leads to anomalous (non-Fickian) transport behavior, the origin of which remains a matter of debate: whether it arises from variability in fracture permeability (velocity distribution), connectedness in the flow paths through fractures (velocity correlation), or interaction between fractures and matrix. Here we show that this uncertainty of distribution-versus correlation-controlled transport can be resolved by combining convergent and push-pull tracer tests because flow reversibility is strongly dependent on velocity correlation, whereas late-time scaling of breakthrough curves is mainly controlled by velocity distribution. We build on this insight, and propose a Lagrangian statistical model that takes the form of a continuous time random walk (CTRW) with correlated particle velocities. In this framework, velocity distribution and velocity correlation are quantified by a Markov process of particle transition times that is characterized by a distribution function and a transition probability. Our transport model accurately captures the anomalous behavior in the breakthrough curves for both push-pull and convergent flow geometries, with the same set of parameters. Thus, the proposed correlated CTRW modeling approach provides a simple yet powerful framework for characterizing the impact of velocity distribution and correlation on transport in fractured media.

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Pore‐scale intermittent velocity structure underpinning anomalous transport through 3‐D porous media

Abstract: 19.12.14 KB. Ok to add published version to spiral after 6 months embargo - expires 15 March 201

Cited by 153 publications

References 43 publications

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

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

Simulating anomalous dispersion in porous media using the unstructured lattice Boltzmann method

Impact of velocity correlation and distribution on transport in fractured media: Field evidence and theoretical model

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