Fluids’ dynamics in transient air sparging of a heterogeneous unconfined aquifer

Al-Maamari, Rashid S.; Hirayama, Akihiko; Shiga, Tsuyoshi; Sueyoshi, Mark; Al-Shuely, Mahfoodh; Abdalla, Osman; Kacimov, A. R.

doi:10.1007/s12665-010-0793-y

Cited by 11 publications

(7 citation statements)

References 26 publications

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“…In the case of aquifer contamination by NAPLs, a common remediation technique is to either induce a flushing flow from surface ponds, injection-abstraction wells, well galleries, etc. (Fetter 1999;Al-Maamari et al 2011) or to rely on 'natural attenuation' (i.e. to leave the contaminated soil/rock to periodic leaching by rainfall-induced infiltration).…”

Section: Engineering Motivation In Contaminant Hydrologymentioning

confidence: 99%

Accumulation of a light non-aqueous phase liquid on a flat barrier baffling a descending groundwater flow

Kacimov

2012

Proc. R. Soc. A.

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The pioneering solution of Zhukovskii for a steady two-dimensional flow of an ideal heavy fluid with a nonlinear free boundary condition is extended to a Darcian flow of groundwater encumbered by an impermeable barrier. The stoss or/and lee sides of the barrier are covered by a macrovolume of a liquid contaminant. Explicit parametric equations of the sharp interface are obtained by inversion of the hodograph domain. Zhukovskii's gas-finger shape is shown to be a particular case of our new class of free surfaces. For a cap of a light liquid, partially covering the roof, from the given crosssectional area of the cap, the affixes of the conformal mapping are found as a solution of a system of two nonlinear equations. The horizontal width and vertical height of the cap are determined. If the dimensionless incident velocity is higher than the density contrast, then the interface (cap boundary) cusps at its apex. For a relatively small velocity, the interface spreads to the vertices of the barrier, the apex zone remaining blunt shaped. We depict all the relevant domains and plot the flow nets using computer algebra routines.Keywords: nonlinear free boundary problem; two-dimensional flow of heavy ideal fluid -seepage; holomorphic functions; hodograph; conformal mappings Historical motivation from Zhukovskii's solutionThere are very few analytical solutions to the problem of steady two-dimensional motion of an ideal irrotational heavy fluid with a free surface. This is caused by the necessity to satisfy the Bernoulli equationalong an unknown isobaric streamline (free surface). In equation (1.1a), V is the magnitude of the velocity vector V = V e iq , q is the angle that V makes with the horizontal axis x, g = 9.8 m s −2 and y is the vertical coordinate oriented upwards, against gravity.

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Section: Engineering Motivation In Contaminant Hydrologymentioning

confidence: 99%

Accumulation of a light non-aqueous phase liquid on a flat barrier baffling a descending groundwater flow

Kacimov

2012

Proc. R. Soc. A.

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“…Illustration of the groundwater level ( GWL ) during pulsed AS in a field study, following Al‐Maamari et al () and Yang et al (). The characteristic time of reaching steady state is denoted by T.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temporal Changes in Air Injection Rate on Air Sparging Performance Groundwater Remediation

Neriah

Paster²

2016

Groundwater

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Air sparging (AS) is a commonly applied method for treating groundwater contaminated with volatile organic compounds (VOCs). When using a constant injection of air (continuous mode), a decline in remediation efficiency is often observed, resulting from insufficient mixing of contaminants at the pore scale. It is well known that turning the injection on and off (pulsed mode) may lead to a better remediation performance. In this article, we investigate groundwater mixing and contaminant removal efficiency in different injection modes (i.e., continuous and pulsed), and compare them to those achieved in a third mode, which we denote as "rate changing." In this mode, injection is always on, and its rate is varying with time by abrupt changes. For the purpose of this investigation, we conducted two separate sets of experiments in a laboratory tank. In the first set of experiments, we used dye plume tracing to characterize the mixing induced by AS. In the second set of experiments, we contaminated the tank with a VOC and compared the remediation efficiency between the different injection modes. As expected, we observed that time-variable injection modes led to enhanced mixing and contaminant removal. The decrease in contaminant concentrations during the experiment was found to be double for the "rate changing" and "pulsed" modes compared to the continuous mode, with a slightly preferable performance for the "rate changing" mode. These results highlight the critical role that mixing plays in AS, and support the need for further investigation of the proposed "rate changing" injection mode.

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“…We emphasize again that the sharp interface model is supersimplistic because it does not take into account the heterogeneity of the soil, capillarity, partial saturation of the void space by three contacting phases (air, LNAPL, and water), and, correspondingly, phase permeabilities, the transient effects of LNAPL accumulation in the lens and its digestion by slow dissolution and ensuing diffusional‐dispersive transport of oil toward the well, the volatalization of LNAPL and its loss through the flat gas‐oil interface, etc. This model qualitatively predicts, however, the experimental results in a sand box and observations in the field [ Al‐Maamari et al , 2011]. Unlike the analytical multiphase model [see Bear and Ryzhik , 1998, and references therein], our model does not assume a vertical equilibrium (hydrostatic pressure) in flowing water (although LNAPL is virtually static).…”

Section: Discussionmentioning

confidence: 78%

How much floating light nonaqueous phase liquid can a phreatic surface sustain? Riesenkampf's scheme revisited

Kacimov

Al‐Maktoumi

Al-Balushi

2011

Water Resources Research

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[1] Steady, Darcian, one-phase, phreatic surface flow of groundwater into a horizontal well with a pancake lens of light nonaqueous phase liquid (LNAPL) accumulated in the water table trough is studied by the method of complex analysis. A sharp interface model assumes groundwater capped by two isobaric limbs (groundwater-vadose zone interfaces) of a free surface with an in-between cambered segment of an immiscible LNAPL-water interface, along which pressure is hydrostatically increasing with the depth of the LNAPL ''channel.'' The complex potential polygon is mapped onto an auxiliary half plane where the complex physical coordinate of the flow domain is represented in terms of singular integrals as a solution of the Keldysh-Sedov problem. The shapes of semi-infinite ''wings'' of the water table contacting the vadose zone gas and of a finite length LNAPL-groundwater interface are found from parametric equations that involve the sink strength and location with respect to the pancake surface, the ordinate of the lowest trough point, and the volume of LNAPL accreted in the lens. Critical conditions, corresponding to the lens contour cusping toward the sink, are found. The Riesenkampf solution contains a free parameter, which is fixed by specifying either a point on the free surface or the volume of the trough-intercepted LNAPL.

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Fluids’ dynamics in transient air sparging of a heterogeneous unconfined aquifer

Cited by 11 publications

References 26 publications

Accumulation of a light non-aqueous phase liquid on a flat barrier baffling a descending groundwater flow

Accumulation of a light non-aqueous phase liquid on a flat barrier baffling a descending groundwater flow

Effect of Temporal Changes in Air Injection Rate on Air Sparging Performance Groundwater Remediation

How much floating light nonaqueous phase liquid can a phreatic surface sustain? Riesenkampf's scheme revisited

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