Analysis of 'Investigating an extended multiphase flow model that includes specific interfacial area', Computer Methods in Applied Mechanics and Engineering, 418:116594, 2024.

Comments are provided on the recent paper by Ebadi et al. [3], which demonstrates that the formulated model that was solved contains misconceptions or errors that render the work unsuitable for describing the evolution of interfacial areas in two-fluid porous medium systems. The need for kinematic equations is described and components of a theoretically consistent approach are summarized.

Modeling flow of Carreau fluids in porous media.

Carreau fluids occur routinely in porous medium systems for a range of applications, and the dependence of the viscosity for such fluids on the rate of strain tensor poses challenges to modeling at an averaged macroscale. Traditional approaches for macroscale modeling such flows have relied upon experimental observations of flows for generalized Newtonian fluids (GNFs) and a phenomenological approach referred to herein as the shift factor. A recently developed approach based upon averaging conservation and thermodynamic equations from the microscale for Cross model GNFs is extended to the case of Carreau fluids and shown to predict the flow through both isotropic and anisotropic media accurately without the need for GNF-flow experiments.

A modular microfluidic device that uses magnetically actuatable microposts for enhanced magnetic bead-based workflows.

Magnetic beads have been widely and successfully used for target enrichment in life science assays. There exists a large variety of commercially available magnetic beads functionalized for specific target capture, as well as options that enable simple surface modifications for custom applications. While magnetic beads are ideal for use in the macrofluidic context of typical laboratory workflows, their performance drops in microfluidic contexts, such as consumables for point-of-care diagnostics.

Towards Understanding Factors Affecting Arsenic, Chromium, and Vanadium Mobility in the Subsurface.

Arsenic (As), chromium (Cr), and vanadium (V) are naturally occurring, redox-active elements that can become human health hazards when they are released from aquifer substrates into groundwater that may be used as domestic or irrigation source. As such, there is a need to develop incisive conceptual and quantitative models of the geochemistry and transport of potentially hazardous elements to assess risk and facilitate interventions. However, understanding the complexity and heterogeneous subsurface environment requires knowledge of solid-phase minerals, hydrologic movement, aerobic and anaerobic environments, microbial interactions, and complicated chemical kinetics.

A continuum mechanical framework for modeling tumor growth and treatment in two- and three-phase systems.

The growth and treatment of tumors is an important problem to society that involves the manifestation of cellular phenomena at length scales on the order of centimeters. Continuum mechanical approaches are being increasingly used to model tumors at the largest length scales of concern. The issue of how to best connect such descriptions to smaller-scale descriptions remains open.

Molecular Methods for Assessing the Morphology, Topology, and Performance of Polyamide Membranes.

The molecular-scale morphology and topology of polyamide composite membranes determine the performance characteristics of these materials. However, molecular-scale simulations are computationally expensive and morphological and topological characterization of molecular structures are not well developed. Molecular dynamics simulation and analysis methods for the polymerization, hydration, and quantification of polyamide membrane structures were developed and compared to elucidate efficient approaches for producing and analyzing the polyamide structure.

Generalized Newtonian fluid flow in porous media.

Single-fluid-phase porous medium systems are typically modeled at an averaged length scale termed the macroscale, and Darcy's law is typically relied upon as an approximation of the momentum equation under Stokes flow conditions. Standard approaches for modeling macroscale single-fluid-phase flow of generalized Newtonian fluids (GNFs) extend the standard Newtonian model based upon Darcy's law using an effective viscosity and assuming that the intrinsic permeability is invariant with respect to fluid properties. This approach results in a need to perform an experiment for a non-Newtonian fluid, the introduction of effective parameters that are not tied to known microscale physics, and uncertainty regarding the dependencies of the fitted empirical parameter on system properties.

Gender Differences and Their Influences on T2DM Self-Management Among Spanish-Speaking Latinx Immigrants.

Introduction: Evidence suggests that gender may influence many aspects of type 2 diabetes (T2DM) self-management (SM) and we posit that limited English language-proficient Latinx immigrants face additional challenges.

Methods: Instruments and semi-structured interviews were used to examine gender differences on health literacy, diabetes knowledge, health-promoting behaviors, diabetes, eating and exercise self-efficacy (SE), and T2DM SM practices among a cohort of limited English language-proficient Latinx immigrants. Statistical and qualitative analysis procedures were performed comparing males and females.

Microscale modeling of nondilute flow and transport in porous medium systems.

Nondilute transport occurs routinely in porous medium systems. Experimental observations have revealed effects that seemingly depend upon density, viscosity, velocity, and chemical activity. Macroscale models based upon averaged behavior over many pores have been relied upon to describe such systems to date, which require parametrization of important physical phenomena in material coefficients.

Modeling cross model non-Newtonian fluid flow in porous media.

Fluids exhibiting non-Newtonian rheologies are used in a range of applications, including hydraulic fracturing, enhanced oil recovery, remediation, and industrial processes. Hydraulic fracturing in particular has received attention from environmental scientists, policy-makers, and the general public due in part to concerns about the possibility of contamination of groundwater resources by the complex and potentially harmful fluids used in the process. The non-Newtonian nature of many hydraulic fracturing fluids complicates the prediction of their movement, and precludes use of most traditional flow and transport models.

The Space Between: Transformative Learning and Type 2 Diabetes Self-Management.

Introduction: Immigrant populations experience higher type 2 diabetes mellitus (T2DM) prevalence rates and worse health outcomes secondary to T2DM than native-born populations. But as the largest immigrant population in the United States, the experience of T2DM diagnosis and self-management among Spanish-speaking, limited English-language proficient Latinx immigrants remains largely unexamined. This study used semistructured interviews to explore these phenomena among a cohort of 30 recent Latinx immigrants.

Thermodynamically Constrained Averaging Theory: Principles, Model Hierarchies, and Deviation Kinetic Energy Extensions.

The thermodynamically constrained averaging theory (TCAT) is a comprehensive theory used to formulate hierarchies of multiphase, multiscale models that are closed based upon the second law of thermodynamics. The rate of entropy production is posed in terms of the product of fluxes and forces of dissipative processes. The attractive features of TCAT include consistency across disparate length scales; thermodynamic consistency across scales; the inclusion of interfaces and common curves as well as phases; the development of kinematic equations to provide closure relations for geometric extent measures; and a structured approach to model building.

Diabetes affects everything: Type 2 diabetes self-management among Spanish-speaking hispanic immigrants.

This article is a report of qualitative findings of a mixed-methods study of the relationships among knowledge, self-efficacy, health promoting behaviors, and type 2 diabetes mellitus (T2DM) self-management among limited-english-proficient recent Hispanic immigrants, a population with increased incidence of T2DM and barriers to successful T2DM management. Semi-structured interviews were conducted with 30 participants, and physiological and demographic data also were collected. The participants generally attributed developing the disease to strong emotions and viewed T2DM as a serious disease.

Type 2 Diabetes Self-management Among Spanish-Speaking Hispanic Immigrants.

This article describes the quantitative findings of a mixed-methods study that examined the relationship among knowledge, self-efficacy, health promoting behaviors, and type 2 diabetes self-management among recent Spanish-speaking, limited English proficient immigrants to the US. This population is at risk for both a higher incidence of disease and increased barriers to successful disease management compared to the general US population. Distinguishing aspects of this study compared to the available literature are the comprehensive nature of the data collected, the theoretical component, and the analysis and modeling approach.

Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems.

Multiphase flows in porous medium systems are typically modeled at the macroscale by applying the principles of continuum mechanics to develop models that describe the behavior of averaged quantities, such as fluid pressure and saturation. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating the capillary pressure to fluid saturation and, in some cases, other topological invariants such as interfacial area and the Euler characteristic (or average Gaussian curvature).

A comparison of physicochemical methods for the remediation of porous medium systems contaminated with tar.

The remediation of former manufactured gas plant (FMGP) sites contaminated with tar DNAPLs (dense non-aqueous phase liquids) presents a significant challenge. The tars are viscous mixtures of thousands of individual compounds, including known and suspected carcinogens. This work investigates the use of combinations of mobilization, solubilization, and chemical oxidation approaches to remove and degrade tars and tar components in porous medium systems.

Averaging Theory for Description of Environmental Problems: What Have We Learned?

Advances in Water Resources has been a prime archival source for implementation of averaging theories in changing the scale at which processes of importance in environmental modeling are described. Thus in celebration of the 35th year of this journal, it seems appropriate to assess what has been learned about these theories and about their utility in describing systems of interest. We review advances in understanding and use of averaging theories to describe porous medium flow and transport at the macroscale, an averaged scale that models spatial variability, and at the megascale, an integral scale that only considers time variation of system properties.

Compositional and pH effects on the interfacial tension between complex tar mixtures and aqueous solutions.

Tars at former manufactured gas plants (FMGPs) are a major environmental concern and present a number of challenges to remediators. This experimental study investigates the relationship between composition and tar-water interfacial tension (IFT), a property of primary importance in determining the transport of tar in porous media. Nine field-collected FMGP tars and a commercially available coal tar were characterized by means of fractionation, gas chromatography, Fourier transform infrared (FTIR) spectrometry, and vapor pressure osmometry.

Mobilization of manufactured gas plant tar with alkaline flushing solutions.

This experimental study investigates the use of alkaline and alkaline-polymer solutions for the mobilization of former manufactured gas plant (FMGP) tars. Tar-aqueous interfacial tensions (IFTs) and contact angles were measured, and column flushing experiments were conducted. NaOH solutions (0.

TCAT Analysis of Capillary Pressure in Non-equilibrium, Two-fluid-phase, Porous Medium Systems.

Standard models of flow of two immiscible fluids in a porous medium make use of an expression for the dependence of capillary pressure on the saturation of a fluid phase. Data to support the mathematical expression is most often obtained through a sequence of equilibrium experiments. In addition to such expressions being hysteretic, recent experimental and theoretical studies have suggested that the equilibrium functional forms obtained may be inadequate for modeling dynamic systems.

Thermodynamically Constrained Averaging Theory Approach for Modeling Flow and Transport Phenomena in Porous Medium Systems: 8. Interface and Common Curve Dynamics.

This work is the eighth in a series that develops the fundamental aspects of the thermodynamically constrained averaging theory (TCAT) that allows for a systematic increase in the scale at which multiphase transport phenomena is modeled in porous medium systems. In these systems, the explicit locations of interfaces between phases and common curves, where three or more interfaces meet, are not considered at scales above the microscale. Rather, the densities of these quantities arise as areas per volume or length per volume.

Recovery of phenanthrene-degrading bacteria after simulated in situ persulfate oxidation in contaminated soil.

A continuous-flow column study was conducted to investigate the long-term effects of persulfate oxidation on the abundance and activity of the indigenous microbial community and phenanthrene-degrading bacteria in contaminated soil from a former manufactured gas plant (MGP) site. Approximately six pore volumes of a 20 g/L persulfate solution were introduced into the column, followed by simulated groundwater for 500 days. Soil samples were collected from the surface of the soil bed and along the column length immediately before and after persulfate injection and up to 500 days following injection.

An Evaluation of Solution Algorithms and Numerical Approximation Methods for Modeling an Ion Exchange Process.

The focus of this work is on the modeling of an ion exchange process that occurs in drinking water treatment applications. The model formulation consists of a two-scale model in which a set of microscale diffusion equations representing ion exchange resin particles that vary in size and age are coupled through a boundary condition with a macroscopic ordinary differential equation (ODE), which represents the concentration of a species in a well-mixed reactor. We introduce a new age-averaged model (AAM) that averages all ion exchange particle ages for a given size particle to avoid the expensive Monte-Carlo simulation associated with previous modeling applications.

Thermodynamically Constrained Averaging Theory Approach for Modeling Flow and Transport Phenomena in Porous Medium Systems: 7. Single-Phase Megascale Flow Models.

This work is the seventh in a series that introduces and employs the thermodynamically constrained averaging theory (TCAT) for modeling flow and transport in multiscale porous medium systems. This paper expands the previous analyses in the series by developing models at a scale where spatial variations within the system are not considered. Thus the time variation of variables averaged over the entire system is modeled in relation to fluxes at the boundary of the system.