Computational Aspects in Thermo-Hydro-Mechanical Analysis of Porous Media Part I: Transport Processes

Fundamental, physics-based modeling of complex food processes is still in the developmental stages. This lack of development can be attributed to complexities in both the material and transport processes. Society has a critical need for automating food processes (both in industry and at home) while improving quality and making food safe. Product, process, and equipment designs in food manufacturing require a more detailed understanding of food processes that is possible only through physics-based modeling. The objectives of this paper are (1) to develop a general multicomponent and multiphase modeling framework that can be used for different thermal food processes and can be implemented in commercially available software (for wider use) and (2) to apply the model to the simulation of deep-fat frying and hamburger cooking processes and validate the results. Treating food material as a porous medium, heat and mass transfer inside such material during its thermal processing is described using equations for mass and energy conservation that include binary diffusion, capillary and convective modes of transport, and physicochemical changes in the solid matrix that include phase changes such as melting of fat and water and evaporation/condensation of water. Evaporation/condensation is considered to be distributed throughout the domain and is described by a novel nonequilibrium formulation whose parameters have been discussed in detail. Two complex food processes, deep-fat frying and contact heating of a hamburger patty, representing a large group of common food thermal processes with similar physics have been implemented using the modeling framework. The predictions are validated with experimental results from the literature. As the food (a porous hygroscopic material) is heated from the surface, a zone of evaporation moves from the surface to the interior. Mass transfer due to the pressure gradient (from evaporation) is significant. As temperature rises, the properties of the solid matrix change and the phases of frozen water and fat become transportable, thus affecting the transport processes significantly. Because the modeling framework is general and formulated in a manner that makes it implementable in commercial software, it can be very useful in computer-aided food manufacturing. Beyond its immediate applicability in food processing, such a comprehensive model can be useful in medicine (for thermal therapies such as laser surgery), soil remediation, nuclear waste treatment, and other fields where heat and mass transfer takes place in porous media with significant evaporation and other phase changes.

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Porous media as a canvas for hydro-bio-geo-chemical processes: Facing the challenges

10.5194/egusphere-egu21-15490 ◽

2021 ◽

Author(s):

Xavier Sanchez-Vila

Keyword(s):

Porous Media ◽

Reactive Transport ◽

Field Work ◽

Open Science ◽

Transport Processes ◽

Aquifer Recharge ◽

Music Production ◽

Emerging Compounds ◽

Technological Developments ◽

Large Research

The more we study flow and transport processes in porous media, the larger the number of questions that arise. Heterogeneity, uncertainty, multidisciplinarity, and interdisciplinarity are key words that make our live as researchers miserable&#8230; and interesting. There are many ways of facing complexity; this is equivalent as deciding what colors and textures to consider when being placed in front of a fresh canvas, or what are the sounds to include and combine in a music production. You can try to get as much as you can from one discipline, using very sophisticated state-of-the-art models. On the other hand, you can choose to bring to any given problem a number of disciplines, maybe having to sacrifice deepness in exchange of the better good of yet still sophisticated multifaceted solutions. There are quite a number of examples of the latter approach. In this talk, I will present a few of those, eventually concentrating in managed aquifer recharge (MAR) practices. This technology involves water resources from a myriad of perspectives, covering from climate change to legislation, from social awareness to reactive transport, from toxicological issues to biofilm formation, from circular economy to emerging compounds, from research to pure technological developments, and more. All of these elements deserve our attention as researchers, and we cannot pretend to master all of them. Integration, development of large research groups, open science are words that will appear in this talk. So does mathematics, and physics, and geochemistry, and organic chemistry, and biology. In any given hydrogeological problem you might need to combine equations, statistics, experiments, field work, and modeling; expect all of them in this talk. As groundwater complexity keeps amazing and mesmerizing me, do not expect solutions being provided, just anticipate more and more challenging research questions being asked.

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Review on the Macro-Transport Processes Theory for Irregular Pores able to Perform Catalytic Reactions

Catalysts ◽

10.3390/catal9030281 ◽

2019 ◽

Vol 9 (3) ◽

pp. 281 ◽

Cited By ~ 4

Author(s):

Iván Santamaría-Holek ◽

Saúl Hernández ◽

Consuelo García-Alcántara ◽

Aldo Ledesma-Durán

Keyword(s):

Porous Media ◽

Diffusion Coefficients ◽

Mass Conservation ◽

Breakthrough Curves ◽

Transport Processes ◽

Catalytic Reactions ◽

Irregular Domains ◽

Surface Mass ◽

Physicochemical Basis ◽

Mass Uptake

We review and generalize a recent theoretical framework that provides a sound physicochemical basis to describe how volume and surface diffusion are affected by adsorption and desorption processes, as well as by catalytic conversion within the space defined by the irregular geometry of the pores in a material. The theory is based on two single-dimensional mass conservation equations for irregular domains deduced for the volumetric (bulk) and surface mass concentrations. It offers a powerful tool for analyzing and modeling mass transport across porous media like zeolites or artificially build materials, since it establishes how the microscopic quantities that refer to the internal details of the geometry, the flow and the interactions within the irregular pore can be translated into macroscopic variables that are currently measured in experiments. The use of the theory in mass uptake experiments is explained in terms of breakthrough curves and effective mass diffusion coefficients which are explicitly related to the internal geometry of the pores.

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Electrokinetic-enhanced removal of toluene from physically heterogeneous granular porous media

Quarterly Journal of Engineering Geology and Hydrogeology ◽

10.1144/qjegh2020-073 ◽

2020 ◽

pp. qjegh2020-073

Author(s):

Richard Thomas Gill ◽

Steven Thornton ◽

Michael J. Harbottle ◽

Jonathan W. N. Smith

Keyword(s):

Porous Media ◽

Transport Processes ◽

Effective Mechanism ◽

Content Type ◽

Bench Scale ◽

Toluene Concentration ◽

Granular Porous Media ◽

Supplementary Material ◽

Scale Experiment ◽

Water Saturated

Electrokinetics (EK) was applied to enhance biodegradation of toluene in the low hydraulic conductivity (K) zone of a physically heterogeneous water-saturated granular porous media. The hypothesis tested was that EK transport processes, which operate independently of advection, can deliver a limiting amendment, nitrate, across a high-K–low-K boundary to stimulate bioremediation. Two types of experiment were evaluated: (1) bench-scale tests that represented the active EK system and physically heterogeneous sediment configuration; (2) microcosms that represented biodegradation in the bench-scale tests under ideal conditions. The bench-scale experiment results showed a rapid decrease in toluene concentration during the application of EK that was attributed to electroosmotic removal from low-K zones. Comparison of toluene removal rates by electroosmosis and biodegradation (microcosm) confirmed that electroosmosis was the most effective mechanism under the conditions evaluated. Overall, this work challenges the original hypothesis and indicates that, at the field scale, the most favourable conditions for biodegradation are likely to be achieved by applying EK to increase contaminant flux across the low-K–high-K boundary (out of the low-K zone) and allowing biodegradation to occur in the high-K zone either by natural attenuation or enhanced by amendment addition.Supplementary material: Supplementary material is available at https://doi.org/10.6084/m9.figshare.c.5174554

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Historical development of soil-water physics and solute transport in porous media

Water Science & Technology Water Supply ◽

10.2166/ws.2007.007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 59-66 ◽

Cited By ~ 4

Author(s):

D.E. Rolston

Keyword(s):

Porous Media ◽

Hydraulic Conductivity ◽

Solute Transport ◽

Soil Water ◽

20Th Century ◽

Water Flow ◽

Unsaturated Soils ◽

Transport Processes ◽

Transport In Porous Media ◽

Unsaturated Hydraulic Conductivity

The science of soil-water physics and contaminant transport in porous media began a little more than a century ago. The first equation to quantify the flow of water is attributed to Darcy. The next major development for unsaturated media was made by Buckingham in 1907. Buckingham quantified the energy state of soil water based on the thermodynamic potential energy. Buckingham then introduced the concept of unsaturated hydraulic conductivity, a function of water content. The water flux as the product of the unsaturated hydraulic conductivity and the total potential gradient has become the accepted Buckingham-Darcy law. Two decades later, Richards applied the continuity equation to Buckingham's equation and obtained a general partial differential equation describing water flow in unsaturated soils. For combined water and solute transport, it had been recognized since the latter half of the 19th century that salts and water do not move uniformly. It wasn't until the middle of the 20th century that scientists began to understand the complex processes of diffusion, dispersion, and convection and to develop mathematical formulations for solute transport. Knowledge on water flow and solute transport processes has expanded greatly since the early part of the 20th century to the present.

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Global random walk solvers for fully coupled flow and transport in saturated/unsaturated porous media

10.5194/egusphere-egu21-1941 ◽

2021 ◽

Author(s):

Nicolae Suciu ◽

Davide Illiano ◽

Alexander Prechtel ◽

Florin Radu

Keyword(s):

Finite Element ◽

Porous Media ◽

Random Walk ◽

Transport Processes ◽

Richards Equation ◽

Unsaturated Porous Media ◽

Coupled Flow ◽

Flow And Transport ◽

Coupled Flow And Transport ◽

Fully Coupled

We present new random walk methods to solve flow and transport problems in saturated/unsaturated porous media, including coupled flow and transport processes in soils, heterogeneous systems modeled through random hydraulic conductivity and recharge fields, processes at the field and regional scales. The numerical schemes are based on global random walk algorithms (GRW) which approximate the solution by moving large numbers of computational particles on regular lattices according to specific random walk rules. To cope with the nonlinearity and the degeneracy of the Richards equation and of the coupled system, we implemented the GRW algorithms by employing linearization techniques similar to the L-scheme developed in finite element/volume approaches. The resulting GRW L-schemes converge with the number of iterations and provide numerical solutions that are first-order accurate in time and second-order in space. A remarkable property of the flow and transport GRW solutions is that they are practically free of numerical diffusion. The GRW solvers are validated by comparisons with mixed finite element and finite volume solvers in one- and two-dimensional benchmark problems. They include Richards' equation fully coupled with the advection-diffusion-reaction equation and capture the transition from unsaturated to saturated flow regimes. &#160;For completeness, we also consider decoupled flow and transport model problems for saturated aquifers.

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The Modelling of Multiphase Flow and Transport Processes in Porous Media

Soil & Environment - Contaminated Soil ’95 ◽

10.1007/978-94-011-0415-9_46 ◽

1995 ◽

pp. 221-222

Author(s):

Vincent Lagendijk ◽

Axel Braxein ◽

Christian Forkel ◽

Gerhard Rouvé

Keyword(s):

Porous Media ◽

Multiphase Flow ◽

Transport Processes ◽

Flow And Transport

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Vadose Zone, Part I : Characterization and Flow Processes

Applied Stochastic Hydrogeology ◽

10.1093/oso/9780195138047.003.0016 ◽

2003 ◽

Author(s):

Yoram Rubin

Keyword(s):

Porous Media ◽

Water Flow ◽

Governing Equation ◽

Vadose Zone ◽

Stochastic Analysis ◽

Transport Processes ◽

Richards Equation ◽

Saturated Porous Media ◽

Flow And Transport ◽

Flow Processes

Many of the principles guiding stochastic analysis of flow and transport processes in the vadose zone are those which we also employ in the saturated zone, and which we have explored in earlier chapters. However, there are important considerations and simplifications to be made, given the nature of the flow and of the governing equations, which we explore here and in chapter 12. The governing equation for water flow in variably saturated porous media at the smallest scale where Darcy’s law is applicable (i.e., no need for upscaling of parameters) is Richards’ equation (cf. Yeh, 1998)

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