Comment on “Averaging theory for description of environmental problems: What have we learned?” by William G. Gray, Cass T. Miller, and Bernhard A. Schrefler

Baveye, Philippe C.

doi:10.1016/j.advwatres.2012.08.012

Cited by 8 publications

(4 citation statements)

References 56 publications

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“…In this respect, a multiplicity of immiscible continuum theories of mixtures has been proposed, see, e.g., the many works referenced in surveys (Baveye, 2013;Bedford and Drumheller, 1983;Gray et al, 2013), although these do not often collimate neither in the macroscopic balance equations (Albers and Wilmanski, 2006;Biot, 1955;Bowen, 1982;Goodman and Cowin, 1972;Hassanizadeh and Gray, 1979;Wilmanski, 1998), nor for the very physical-mathematical, or engineering, definition considered to introduce macroscopic stress measures in the theory (Bedford and Drumheller, 1979;Biot and Willis, 1957;Bishop, 1959; http://dx.doi.org/10.1016/j.ijsolstr.2014.10.033 0020-7683/Ó 2014 Elsevier Ltd. All rights reserved. Coussy et al, 1998;de Boer and Ehlers, 1990;de Boer, 2005;Gray and Hassanizadeh, 1991;Gray et al, 2009;Lancellotta, 2002;Nur and Byerlee, 1971;Schrefler, 2002;Skempton, 1960a;Wilmanski, 2004).…”

Section: Introductionmentioning

confidence: 99%

Variationally consistent derivation of the stress partitioning law in saturated porous media

Serpieri

Travascio

Asfour

et al. 2015

International Journal of Solids and Structures

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a b s t r a c tThe linearized version of a recently formulated Variational Macroscopic Theory of biphasic isotropic Porous Media (VMTPM) is employed to derive a general stress partitioning law for media undergoing flow conditions under prevented fluid seepage and negligible inertia effects, typically met in biphasic specimens subjected to jacketed tests.The principle of virtual work, relevant to the specialization of VMTPM to such characteristic flow conditions, naturally yields a stress partitioning law, between solid and fluid phase of a saturated medium, that exactly matches with the celebrated Terzaghi's principle. It is also shown that the stress tensor of the solid phase work-associated with the strain measure of the VMTPM naturally corresponds to the Terzaghi's effective stress. Accordingly, under undrained conditions, Terzaghi's law is proved to be a completely general stress partitioning law for a saturated biphasic medium irrespective of its constitutive and/or microstructural features as well as of the compressibility of its constituent phases.Since the developments reported are obtained ruling out thermodynamic constraints and any assumption on the internal microstructure and on the compressibility of the phases, the results obtained indicate that Terzaghi's law could more generally apply to a broader class of biphasic media and be not restricted within the context of geomechanics.

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Section: Introductionmentioning

confidence: 99%

Variationally consistent derivation of the stress partitioning law in saturated porous media

Serpieri

Travascio

Asfour

et al. 2015

International Journal of Solids and Structures

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“…In temperate regions, the top soil often behaves as an unsaturated porous medium, where liquid water content is reliably measured (Kidron & Kronenfeld, 2020; Kizito et al., 2008), albeit on a relatively coarse spatial resolution. There, the principal challenge is to specify the water retention curve, a history‐dependent relation between water volume fraction and capillary pressure subject to “return‐point” memory hysteresis, which is predictable for known pore networks (Xu & Louge, 2015), but is typically modeled instead with the Van Genuchten (1980) empirical correlation, see for example, Assouline and Kamai (2019), or with local closures involving meniscus curvature (Gray & Miller, 2005) that elicit controversy (Baveye, 2013).…”

Section: Discussionmentioning

confidence: 99%

Water Vapor Transport Across an Arid Sand Surface—Non‐Linear Thermal Coupling, Wind‐Driven Pore Advection, Subsurface Waves, and Exchange With the Atmospheric Boundary Layer

et al. 2022

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Although vapor exchanged across hyper‐arid surfaces without free liquid affects the water budget of sand seas, its mechanism is poorly documented for want of accurate instruments with fine spatial resolution. To rectify this, we report bulk density profiles and spatiotemporal variations of vapor mass fraction just below the surface of a mobile dune, acquired with a multi‐sensor capacitance probe sensitive to tiny water films adsorbed on sand grains. We also record wind speed and direction, ambient temperature and relative humidity, net radiation flux, and subsurface temperature profiles over 2 days. The data validate a non‐linear model of vapor mass fraction. Unlike heat, which conducts through grains, vapor percolates across the interstitial pore space by advection and diffusion. On time scales longer than evaporation, adsorbed films equilibrate with their surroundings and hinder molecular diffusion. Their non‐linear coupling with subsurface temperature generates inflections in vapor profiles without counterpart in simpler diffusive systems. Pore advection arises as wind induces subtle pressure variations over the topography. During periods of aeolian transport, flowing sand dehydrates the surface intermittently, triggering evanescent vapor waves of amplitude decaying exponentially downward on a characteristic length implying an adsorption rate governed by a kinetic‐limited activated process. Finally, the probe yields diffusive and advective exchanges with the atmospheric boundary layer. During the day, their combined flux is smaller than expected, yet nearly proportional to the difference between vapor mass fraction at the surface and aloft. Under stabler stratification at night, or during aeolian sand transport, this relation no longer holds.

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“…Another option, which has been used by numerous authors over the last two decades, consists of averaging microscopic descriptions of porous media, over either a Representative Elementary Volume or an arbitrary volume (e.g., associated with a measuring instrument), in order to obtain macroscopic variables ( Ayub and Bentsen, 1999 ; Lichtner and Kang, 2007a , b ; Golfier et al, 2009 ; Valdes-Parada et al, 2009 ; Wood, 2009 , 2010 ; Davit et al, 2010 ; Baveye, 2013a ; Lugo-Mendez et al, 2015 ). Davit et al (2013) have shown that in terms of outcome, this approach is equivalent to another popular upscaling method involving homogenization through multiscale asymptotics (e.g., Roose et al, 2016 ).…”

Section: Upscaling How?mentioning

confidence: 99%

Emergent Properties of Microbial Activity in Heterogeneous Soil Microenvironments: Different Research Approaches Are Slowly Converging, Yet Major Challenges Remain

et al. 2018

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Over the last 60 years, soil microbiologists have accumulated a wealth of experimental data showing that the bulk, macroscopic parameters (e.g., granulometry, pH, soil organic matter, and biomass contents) commonly used to characterize soils provide insufficient information to describe quantitatively the activity of soil microorganisms and some of its outcomes, like the emission of greenhouse gasses. Clearly, new, more appropriate macroscopic parameters are needed, which reflect better the spatial heterogeneity of soils at the microscale (i.e., the pore scale) that is commensurate with the habitat of many microorganisms. For a long time, spectroscopic and microscopic tools were lacking to quantify processes at that scale, but major technological advances over the last 15 years have made suitable equipment available to researchers. In this context, the objective of the present article is to review progress achieved to date in the significant research program that has ensued. This program can be rationalized as a sequence of steps, namely the quantification and modeling of the physical-, (bio)chemical-, and microbiological properties of soils, the integration of these different perspectives into a unified theory, its upscaling to the macroscopic scale, and, eventually, the development of new approaches to measure macroscopic soil characteristics. At this stage, significant progress has been achieved on the physical front, and to a lesser extent on the (bio)chemical one as well, both in terms of experiments and modeling. With regard to the microbial aspects, although a lot of work has been devoted to the modeling of bacterial and fungal activity in soils at the pore scale, the appropriateness of model assumptions cannot be readily assessed because of the scarcity of relevant experimental data. For significant progress to be made, it is crucial to make sure that research on the microbial components of soil systems does not keep lagging behind the work on the physical and (bio)chemical characteristics. Concerning the subsequent steps in the program, very little integration of the various disciplinary perspectives has occurred so far, and, as a result, researchers have not yet been able to tackle the scaling up to the macroscopic level. Many challenges, some of them daunting, remain on the path ahead. Fortunately, a number of these challenges may be resolved by brand new measuring equipment that will become commercially available in the very near future.

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Comment on “Averaging theory for description of environmental problems: What have we learned?” by William G. Gray, Cass T. Miller, and Bernhard A. Schrefler

Cited by 8 publications

References 56 publications

Variationally consistent derivation of the stress partitioning law in saturated porous media

Variationally consistent derivation of the stress partitioning law in saturated porous media

Water Vapor Transport Across an Arid Sand Surface—Non‐Linear Thermal Coupling, Wind‐Driven Pore Advection, Subsurface Waves, and Exchange With the Atmospheric Boundary Layer

Emergent Properties of Microbial Activity in Heterogeneous Soil Microenvironments: Different Research Approaches Are Slowly Converging, Yet Major Challenges Remain

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