Longitudinal and Transverse Dispersion in Porous Media

Delgado, J. M. P. Q.

doi:10.1205/cherd07017

Cited by 240 publications

(188 citation statements)

References 38 publications

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“…For example, the transverse dispersion coefficients in a staggered array (Edwards et al 1991) are larger than for the situation of a single sphere in a square. However, the values are still much smaller than experimental values (Delgado 2007). It can be expected that better results can be obtained for more complicated unit cells, but such a cell must have isotropic properties as otherwise longitudinal dispersion mixes in the transverse dispersion.…”

Section: Resultsmentioning

confidence: 78%

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Computation of the Longitudinal and Transverse Dispersion Coefficient in an Adsorbing Porous Medium Using Homogenization

2011

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This article compares for the first time, local longitudinal and transverse dispersion coefficients obtained by homogenization with experimental data of dispersion coefficients in porous media, using the correct porosity dependence. It is shown that the longitudinal dispersion coefficient can be reasonably represented by a simple periodic unit cell (PUC), which consists of a single sphere in a cube. We present a slightly modified and simplified approach to derive the homogenized equations, which emphasizes physical aspects of homogenization. Subsequently, we give full dimensional expressions for the dispersion tensor based on a comparison with the convective dispersion equation used for contaminant transport, inclusive the correct dependence on porosity. For the PUC of choice, the dispersion relations are identical to the relations obtained for periodic media. We show that commercial finite element software can be readily used to compute longitudinal and transverse dispersion coefficients in 2D and 3D. The 3D results are for the first time obtained at relevant Peclet numbers. There is good agreement for longitudinal dispersion. The computed transverse dispersion coefficients for a single sphere in a cube are much too low. The effect of adsorption on the dispersion coefficient is also studied. Adsorption does not affect the transverse dispersion coefficient. However, adsorption enhances the longitudinal dispersion coefficient in agreement with an analysis of homogenization applied to Taylor dispersion discussed in the literature.

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Section: Resultsmentioning

confidence: 78%

“…There are excellent overview articles for experimental data (Delgado 2006(Delgado , 2007 of longitudinal and transverse dispersion (Wronski and Molga 1987). These studies mention effects of particle size and particle shape distribution.…”

Section: Resultsmentioning

confidence: 99%

Computation of the Longitudinal and Transverse Dispersion Coefficient in an Adsorbing Porous Medium Using Homogenization

2011

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“…Scaling of the longitudinal hydrodynamic dispersion coefficients (circles for colloids, and triangles for tracer) with Peclet number. The solid line represents the correlation (19) reported by Delgado [2007].…”

Section: Discussionmentioning

confidence: 99%

“…Transverse dispersion coefficients are considerably smaller than longitudinal dispersion coefficients. Numerous correlations, which are typically derived from experimental observations, are available for the estimation of hydrodynamic dispersion coefficients for solute transport in porous media [Delgado, 2006[Delgado, , 2007Olsson and Grathwohl, 2007]. Furthermore, theoretical and numerical procedures have been developed for the estimation of hydrodynamic dispersion coefficients for both periodic as well as heterogeneous porous media.…”

Section: Introductionmentioning

confidence: 99%

Colloid particle size‐dependent dispersivity

Chrysikopoulos,

Katzourakis

2015

Water Resources Research

122

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Laboratory and field studies have demonstrated that dispersion coefficients evaluated by fitting advection-dispersion transport models to nonreactive tracer breakthrough curves do not adequately describe colloid transport under the same flow field conditions. Here an extensive laboratory study was undertaken to assess whether the dispersivity, which traditionally has been considered to be a property of the porous medium, is dependent on colloid particle size and interstitial velocity. A total of 48 colloid transport experiments were performed in columns packed with glass beads under chemically unfavorable colloid attachment conditions. Nine different colloid diameters and various flow velocities were examined. The breakthrough curves were successfully simulated with a mathematical model describing colloid transport in homogeneous, water-saturated porous media. The experimental data set collected in this study demonstrated that the dispersivity is positively correlated with colloid particle size, and increases with increasing velocity. The dispersivity values determined in this laboratory study were compared with 380 dispersivity values from earlier laboratory and field-scale solute, colloid and biocolloid transport studies published in the literature.

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“…Regarding dispersion, results from experiments [11,40] from a thick bed yield the following approximate estimation for the longitudinal dispersion:…”

Section: Governing Equationsmentioning

confidence: 99%

Modelling heat transfer during flow through a random packed bed of spheres

et al. 2017

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Heat transfer in a random packed bed of monosized iron ore pellets is modelled with both a discrete three-dimensional system of spheres and a continuous Computational Fluid Dynamics (CFD) model. Results show a good agreement between the two models for average values over a cross section of the bed for an even temperature profiles at the inlet. The advantage with the discrete model is that it captures local effects such as decreased heat transfer in sections with low speed. The disadvantage is that it is computationally heavy for larger systems of pellets. If averaged values are sufficient, the CFD model is an attractive alternative that is easy to couple to the physics up-and downstream the packed bed. The good agreement between the discrete and continuous model furthermore indicates that the discrete model may be used also on non-Stokian flow in the transitional region between laminar and turbulent flow, as turbulent effects show little influence of the overall heat transfer rates in the continuous model.

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Longitudinal and Transverse Dispersion in Porous Media

Cited by 240 publications

References 38 publications

Computation of the Longitudinal and Transverse Dispersion Coefficient in an Adsorbing Porous Medium Using Homogenization

Computation of the Longitudinal and Transverse Dispersion Coefficient in an Adsorbing Porous Medium Using Homogenization

Colloid particle size‐dependent dispersivity

Modelling heat transfer during flow through a random packed bed of spheres

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