Geometrical and Taylor dispersion in a fracture with random obstacles: An experimental study with fluids of different rheologies

Boschan, Alejandro; Ippolito, I.; Chertcoff, R.; Auradou, Harold; Talon, Laurent; Hulin, Jean-Pierre

doi:10.1029/2007wr006403

Cited by 19 publications

(24 citation statements)

References 32 publications

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“…In complex, fractured media the latter depends mainly on two processes: Aris-Taylor dispersion (D T ) (Aris, 1956) due to the combined action of convection and radial molecular diffusion (Dullien, 1992) and geometrical dispersion (D G ) due to the roughness and/or aperture variation of fractures (Boschan et al, 2008). For a fracture characterized by two flat parallel walls geometrical dispersion should be equal to zero and dispersion processes are represented only by Aris-Taylor dispersion (Auriault, 1995) by the following expression:…”

Section: Solute Transport Modelsmentioning

confidence: 99%

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Evidence of non-Darcy flow and non-Fickian transport in fractured media at laboratory scale

Cherubini

Giasi

Pastore

2013

Hydrol. Earth Syst. Sci.

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Abstract.During a risk assessment procedure as well as when dealing with cleanup and monitoring strategies, accurate predictions of solute propagation in fractured rocks are of particular importance when assessing exposure pathways through which contaminants reach receptors.Experimental data obtained under controlled conditions such as in a laboratory allow to increase the understanding of the fundamental physics of fluid flow and solute transport in fractures.In this study, laboratory hydraulic and tracer tests have been carried out on an artificially created fractured rock sample. The tests regard the analysis of the hydraulic loss and the measurement of breakthrough curves for saline tracer pulse inside a rock sample of parallelepiped shape (0.60 × 0.40 × 0.08 m). The convolution theory has been applied in order to remove the effect of the acquisition apparatus on tracer experiments.The experimental results have shown evidence of a nonDarcy relationship between flow rate and hydraulic loss that is best described by Forchheimer's law. Furthermore, in the flow experiments both inertial and viscous flow terms are not negligible.The observed experimental breakthrough curves of solute transport have been modeled by the classical onedimensional analytical solution for the advection-dispersion equation (ADE) and the single rate mobile-immobile model (MIM). The former model does not properly fit the first arrival and the tail while the latter, which recognizes the existence of mobile and immobile domains for transport, provides a very decent fit.The carried out experiments show that there exists a pronounced mobile-immobile zone interaction that cannot be neglected and that leads to a non-equilibrium behavior of solute transport. The existence of a non-Darcian flow regime has showed to influence the velocity field in that it gives rise to a delay in solute migration with respect to the predicted value assuming linear flow. Furthermore, the presence of inertial effects enhance non-equilibrium behavior. Instead, the presence of a transitional flow regime seems not to exert influence on the behavior of dispersion. The linear-type relationship found between velocity and dispersion demonstrates that for the range of imposed flow rates and for the selected path the geometrical dispersion dominates the mixing processes along the fracture network.

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Section: Solute Transport Modelsmentioning

confidence: 99%

“…In this context understanding transport in a single fracture is a crucial first step (Boschan et al, 2008). Qian et al (2011) carried out well-controlled laboratory experiments to investigate flow and transport in a single fracture under non-Darcy flow conditions.…”

Section: Cherubini Et Al: Evidence Of Non-darcy Flow and Non-fickmentioning

confidence: 99%

Evidence of non-Darcy flow and non-Fickian transport in fractured media at laboratory scale

Cherubini

Giasi

Pastore

2013

Hydrol. Earth Syst. Sci.

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“…The velocity fluctuations (and, as a result, the dispersivity) increase therefore when n decreases i.e when the shear thinning character of the fluids is stronger. Unlike α G , the parameter α T for shear-thinning fluids is lower than the Newtonian value 1/210 (see [18]). The values displayed in Fig.…”

Section: Fracture Modelmentioning

confidence: 99%

“…[18] for details) has two transparent surfaces of size 350 × 120 mm without contact points. The upper one is a flat glass plate and the lower one is a rough photopolymer plate.…”

Section: Experimental Models and Injection Set-upmentioning

confidence: 99%

Miscible transfer of solute in different model fractures: From random to multiscale wall roughness

Auradou¹,

Boschan²,

Chertcoff³

et al. 2009

Comptes Rendus. Géoscience

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Miscible tracer dispersion measurements in transparent model fractures with different types of wall roughness are reported. The nature (Fickian or not) of dispersion is determined by studying variations of the mixing front as a function of the traveled distance but also as a function of the lateral scale over which the tracer concentration is averaged. The dominant convective dispersion mechanisms (velocity profile in the gap, velocity variations in the fracture plane) are established by comparing measurements using Newtonian and shear thinning fluids. For small monodisperse rugosities, front spreading is diffusive with a dominant geometrical dispersion (dispersion coefficient D ∝ Pe) at low Péclet numbers Pe; at higher Pe values one has either D ∝ Pe 2 (i.e. Taylor dispersion) for obstacles of height smaller than the gap or D ∝ Pe 1.35 for obstacles bridging the gap. For a self affine multiscale roughness like in actual rocks and a relative shear displacement δ of complementary walls, the aperture field is channelized in the direction perpendicular to δ. For a mean velocity U parallel to the channels, the global front geometry reflects the velocity contrast between them and is predicted from the aperture field. For U perpendicular to the channels, global front spreading is much reduced. Local spreading of the front thickness remains mostly controlled by Taylor dispersion except in the case of a very strong channelization parallel to U.

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“…Examples include chemical engineering (microfluidics, 1, 2 heterogeneous catalysis, 3, 4 chromatography 5,6 ), biophysics (blood circulation, 7 airflow in lungs, 8 targeted drug delivery 9,10 ), and transport processes in geophysical systems (mixing in atmosphere and ocean, 11,12 flow of gas and water in hydraulically fractured wells, 13 colloid filtration and water purification 14,15 ). It has been well recognized 1,[16][17][18][19] that specifically engineered boundaries can provide an effective means for control of the transport of tracer particles in the confined flow.…”

Section: Introductionmentioning

confidence: 99%

Aris-Taylor dispersion in tubes with dead ends

Dagdug

Berezhkovskii

Skvortsov

2014

The Journal of Chemical Physics

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This paper deals with transport of point Brownian particles in a cylindrical tube with dead ends in the presence of laminar flow of viscous fluid in the cylindrical part of the tube (Poiseuille flow). It is assumed that the dead ends are identical and are formed by spherical cavities connected to the cylindrical part of the tube by narrow necks. The focus is on the effective velocity and diffusivity of the particles as functions of the mean flow velocity and geometric parameter of the tube. Entering a dead end, the particle interrupts its propagation along the tube axis. Later it returns, and the axial motion continues. From the axial propagation point of view, the particle entry into a dead end and its successive return to the flow is equivalent to the particle reversible binding to the tube wall. The effect of reversible binding on the transport parameters has been previously studied assuming that the particle survival probability in the bound state decays as a single exponential. However, this is not the case when the particle enters a dead end, since escape from the dead end is a nonMarkovian process. Our analysis of the problem consists of two steps: First, we derive expressions for the effective transport parameters in the general case of non-Markovian binding. Second, we find the effective velocity and diffusivity by substituting into these expressions known results for the moments

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Geometrical and Taylor dispersion in a fracture with random obstacles: An experimental study with fluids of different rheologies

Cited by 19 publications

References 32 publications

Evidence of non-Darcy flow and non-Fickian transport in fractured media at laboratory scale

Evidence of non-Darcy flow and non-Fickian transport in fractured media at laboratory scale

Miscible transfer of solute in different model fractures: From random to multiscale wall roughness

Aris-Taylor dispersion in tubes with dead ends

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