Characterization of Grain‐Size Distribution, Thermal Conductivity, and Gas Diffusivity in Variably Saturated Binary Sand Mixtures

Journal Article · Thu Aug 23 00:00:00 EDT 2018 · Vadose Zone Journal

DOI:https://doi.org/10.2136/vzj2018.01.0026· OSTI ID:1787379

Deepagoda, T. K. K. Chamindu ^[1]; Smits, Kathleen ^[2]; Jayarathne, J. R. R. N. ^[3]; Wallen, Benjamin M. ^[4]; Clough, Timothy J. ^[5]

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1. Dep. of Civil Engineering Univ. of Peradeniya 20400 Peradeniya Sri Lanka, Dep. of Soil and Physical Sciences Lincoln Univ. P.O. Box 85084 Lincoln 7647 New Zealand
2. Dep. of Civil Engineering Univ. of Texas Arlington TX 76019
3. Dep. of Civil Engineering Univ. of Peradeniya 20400 Peradeniya Sri Lanka
4. Dep. of Geography and Environmental Engineering US Military Academy West Point NY 10996
5. Dep. of Soil and Physical Sciences Lincoln Univ. P.O. Box 85084 Lincoln 7647 New Zealand

Core Ideas Parameterized models are relevant to applications where different porous media mixtures are used. Models include a grain‐size distribution function to describe bimodal behavior for binary mixtures. Improved model describes observed thermal conductivity–saturation relations for binary mixtures. Combined Buckingham–Penman model used to describe observed gas diffusivity–air content relations. This work is relevant for proper simulation of mixed porous media. Characterization of differently textured porous materials, as well as different volumetric porous media mixtures, in relation to mass and heat transport is vital for many engineering and research applications. Functional relations describing physical (e.g., grain‐size distribution, total porosity), thermal, and gas diffusion properties of porous media and mixtures are necessary to optimize the design of porous systems that involve heat and gas transport processes. However, only a limited number of studies provide characterization of soil physical, thermal, and gas diffusion properties and the functional relationships of these properties under varying soil water contents, especially for soil mixtures, complicating optimization efforts. To better understand how mixing controls the physical, thermal, and gas diffusion properties of porous media, a set of laboratory experiments was performed using five volumetric mixtures of coarse‐ and fine‐grained sand particles. For each mixture, the grain‐size distribution (GSD), thermal conductivity, and gas diffusivity were obtained and parameterized using existing and suggested parametric models. Results show that the extended, two‐region Rosin–Rammler particle‐size distribution model proposed in this study could successfully describe the bimodal behavior of the GSD of binary mixtures. Further, the modified Côté and Konrad thermal conductivity model adequately described the thermal conductivity–water saturation relations observed in different mixtures. The proposed simple soil‐gas diffusivity descriptive model parameterized the upper limit, average, and lower limit behavior in gas diffusivity–air content relations in apparently texture‐invariant gas diffusivity data. Results further show a close analogy between gas diffusivity and thermal conductivity and their variation with saturation across different binary mixtures. Overall, the results of the study provide useful numerical insight into the physical, thermal, and gas transport characteristics of binary mixtures, with wide implications for future engineering and research applications that involve multicomponent porous systems.

• Sponsoring Organization: USDOE
• OSTI ID: 1787379
• Alternate ID(s): OSTI ID: 1787382
• Journal Information: Vadose Zone Journal, Journal Name: Vadose Zone Journal Vol. 17 Journal Issue: 1; ISSN 1539-1663
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: United States
• Language: English