Estimation of mechanical dispersion and dispersivity in a soil–gas system by column experiments and the dusty gas model

Hibi, Yoshihiko; Kanou, Yuki; Ohira, Yuki

doi:10.1016/j.jconhyd.2012.01.003

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…It should also be noted that experimental dispersivity accounts for all transport mechanisms not explicitly identified or modeled, and which can change depending on whether the saturation phase is liquid or gas and on the physicochemical properties of the transported species. The amount of data available on gas‐phase dispersivity is very limited [ Hamamoto et al ., ], and most of the recent data on artificial and homogeneous materials [ Gidda et al ., ; Hamamoto et al ., ; Sharma and Poulsen , ; Hibi et al ., ] are in the range 0.001–0.05 m already pointed out by Costanza‐Robinson and Brusseau [].…”

Section: Dispersivity and Processes That Generate Gas Flowmentioning

confidence: 82%

Contribution of mechanical dispersion of vapor to soil evaporation

Grifoll

2013

Water Resources Research

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[1] Conventional methods for numerical simulation of the soil evaporation process do not take into account the mechanical dispersion of vapor in the porous matrix. This omission is due to the uncertainties about the flow process that generates mechanical dispersion and about the numerical value of dispersivity. In this study we assess three processes that can generate mechanical dispersion: (a) temperature variation, (b) barometric pressure variation, and (c) Stefan flow. Order of magnitude estimates show that under natural conditions, only Stefan flow can contribute significantly to the generation of mechanical dispersion. However, a simple sensitivity analysis of the effects of dispersivity on the contribution of different mechanisms to the evaporation process shows that diffusion and mechanical dispersion act in a complementary way. In simulations of a natural system, the evaporation flux increases by only 12% when dispersivity is increased from 0 m (no mechanical dispersion) to 0.078 m, although at the latter value the mechanical dispersion flux contributes up to 40% of the total evaporation flux.

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Section: Dispersivity and Processes That Generate Gas Flowmentioning

confidence: 82%

Contribution of mechanical dispersion of vapor to soil evaporation

Grifoll

2013

Water Resources Research

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“…Although for this fitting we used the ISCCFEM-adq inversion simulator developed by Hibi and colleagues [6,7], which employs a conjugate direction method [8] and a characteristic finite element scheme [9], any general inversion simulator for the advection–diffusion equation can be employed to obtain the effective compound diffusion coefficients and the effective compound velocities of the tracer gases from tracer experiment results.…”

Section: Experimental Procedures and Methods Protocolsmentioning

confidence: 99%

Method for obtaining the Knudsen diffusion coefficient

Hibi

2018

MethodsX

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“…Recently, longitudinal and transverse dispersivities could be determined by the laboratory image analysis using sodium fluorescein as tracer (Citarella et al, 2015), and by laboratory column test using CO2, N2, and O2 gas tracers in the soil contaminated with VOC or petroleum (Hibi et al, 2012).…”

Section: Column Tracer Testmentioning

confidence: 99%

The Characteristics of Hydrogeological Parameters of Unconsolidated Sediments in the Nakdong River Delta of Busan City, Korea

Khakimov¹,

Chung²,

Senapathi³

et al. 2017

Journal of Soil and Groundwater Environment

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This study dealt with the characteristics and the interrelations of hydrogeological parameters such as hydraulic conductivity, dispersivity and effective porosity of unconsolidated sediments for providing the basic data necessary for the planning of the management and preservation of groundwater quality in the Nakdong River Delta of Busan City, Korea. Groundwater quality in this area has been deteriorated due to seawater intrusion, agricultural fertilizer and pesticide, industrial wastewater, and contaminated river water. The physical properties (grain size distribution, sediment type, sorting) and aquifer parameters (hydraulic conductivity, effective porosity, longitudinal dispersivity) were determined from grain size analysis, laboratory permeability test and column tracer test. Among 36 samples, there were 18 Sand (S), 7 Gravelly Sand (gS), 5 Silty Sand (zS), 5 Muddy Sand (mS), and 1 Sandy Silt (sZ). Hydraulic conductivity was determined through a falling head test, and ranged from 9.2 × 10 −5 to 2.9 × 10 −2 cm/sec (0.08 to 25.6 m/day). From breakthrough curves, dispersivity was calculated to be 0.35~3.92 cm. Also, effective porosity and average linear velocity were obtained through the column tracer test, and their values were 0.04~0.46 and 1.06E-04~6.49E-02 cm/sec, respectively. Statistical methods were used to understand the interrelations among aquifer parameters of hydraulic conductivity, effective porosity and dispersivity. The relation between dispersivity and hydraulic conductivity or effective porosity considered the sample length, because dispersivity was affected by experimental scale. The relations between dispersivity and hydraulic conductivity or effective porosity were all in inverse proportion for all long and short samples. The reason was because dispersivity was in inverse proportion to the groundwater velocity in case of steady hydrodynamic dispersion coefficient, and groundwater velocity was in proportion to the hydraulic conductivity or effective porosity. This study also elucidated that longitudinal dispersivity was dependent on the scale of column tracer test, and all hydrogeological parameters were low to high values due to the sand quantity of sediments. It is expected that the hydrogeological parameter data of sediments will be very useful for the planning of groundwater management and preservation in the Nakdong River Delta of Busan City, Korea.

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Estimation of mechanical dispersion and dispersivity in a soil–gas system by column experiments and the dusty gas model

Cited by 10 publications

References 17 publications

Contribution of mechanical dispersion of vapor to soil evaporation

Contribution of mechanical dispersion of vapor to soil evaporation

Method for obtaining the Knudsen diffusion coefficient

The Characteristics of Hydrogeological Parameters of Unconsolidated Sediments in the Nakdong River Delta of Busan City, Korea

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