scholarly journals Development of Permeability Models for Saturated Fluid Flow across Arrays of Fibre Clusters

2002 ◽  
Vol 11 (3) ◽  
pp. 096369350201100
Author(s):  
E.M. Gravel ◽  
T.D. Papathanasiou
Keyword(s):  
Analytical Models ◽  
Dual Porosity ◽  
Hydraulic Permeability ◽  
Fibrous Media ◽  
Fibre Bundles ◽  
Hexagonal Packing ◽  
Composites Manufacturing ◽  
Starting Point ◽  
Wide Range ◽  
Flow Through

Dual porosity fibrous media are important in a number of applications, ranging from bioreactor design and transport in living systems to composites manufacturing. In the present study we are concerned with the development of predictive models for the hydraulic permeability ( Kp) of various arrays of fibre bundles. For this we carry out extensive computations for viscous flow through arrays of fibre bundles using the Boundary Element Method (BEM) implemented on a multi-processor computer. Up to 350 individual filaments, arranged in square or hexagonal packing within bundles, which are also arranged in square of hexagonal packing, are included in each simulation. These are simple but not trivial models for fibrous preforms used in composites manufacturing – dual porosity systems characterised by different inter- and intra-tow porosities. The way these porosities affect the hydraulic permeability of such media is currently unknown and is elucidated through our simulations. Following numerical solution of the governing equations, ( Kp) is calculated from the computed flowrate through Darcy's law and is expressed as function of the inter- and intra-tow porosities (φ, φt) and of the filament radius ( Rf). Numerical results are also compared to analytical models. The latter form the starting point in the development of a dimensionless correlation for the permeability of such dual porosity media. It is found that the numerically computed permeabilities follow that correlation for a wide range of φ i, φt and Rf.

A General Correlation for the Hydraulic Permeability of Arrays of Elliptical Fiber Bundles

2000 ◽  
Author(s):  
E. M. Gravel ◽  
T. D. Papathanasiou
Keyword(s):  
Computational Analysis ◽  
Analytical Models ◽  
Dual Porosity ◽  
Fiber Bundles ◽  
Hydraulic Permeability ◽  
Elliptical Cross ◽  
Single Master Curve ◽  
Flow Through ◽  
The Subject ◽  
Good Agreement

Abstract A computational analysis of viscous flow through arrays of fiber bundles is carried out using the Boundary Element Method. We consider fiber bundles of elliptical cross section, each made up of up to 350 individual filaments. Such arrays are dual-porosity systems, characterized by different inter- (ϕi) and intra-tow (ϕt) porosities as well as by varying number (Nf) of filaments within each bundle. Investigating the influence of these parameters on the hydraulic permeability of hexagonal arrays of such bundles is the subject of our simulations. The results are compared to earlier analytical models and a good agreement is found. A dimensionless correlation is proposed and the computed permeabilities for bundles of aspect ratio λ = 2 and λ = 3 are shown to fall on a single master curve. This offers a generalized model for the calculation of the permeability of such dual porosity systems from knowledge of ϕi, ϕt, λ and Nf.

Parallel Flow Through Ordered Fibers: An Analytical Approach

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
A. Tamayol ◽  
M. Bahrami
Keyword(s):  
Entire Range ◽  
Analytical Approach ◽  
High Porosity ◽  
Fibrous Media ◽  
Fully Developed Flow ◽  
Wide Range ◽  
Hexagonal Arrangement ◽  
Flow Through ◽  
Hexagonal Arrays ◽  
Comparison With Experimental Data

In this study, fully developed flow parallel to ordered fibers is investigated analytically. The considered fibrous media are made up of in-line (square), staggered, and hexagonal arrays of cylinders. Starting from the general solution of Poisson’s equation, compact analytical solutions are proposed for both velocity distribution and permeability of the considered structures. In addition, independent numerical simulations are performed for the considered arrangements over the entire range of porosity and the results are compared with the proposed solutions. The developed solutions are successfully verified through comparison with experimental data, collected by others, and the present numerical results over a wide range of porosity. The results show that for the ordered arrangements with high porosity, the parallel permeability is independent of the microstructure geometrical arrangements; on the other hand, for lower porosities the hexagonal arrangement provides lower pressure drop, as expected.

Numerical Modeling of the Flow of Particle-Filled Resin through a Dual Scale Fibrous Media

2015 ◽  
Vol 1099 ◽  
pp. 44-51
Author(s):  
Hind Haji ◽  
Abdelghani Saouab
Keyword(s):  
Retention Mechanism ◽  
Resin Flow ◽  
Liquid Composite Molding ◽  
Mesoscopic Scale ◽  
Fibrous Media ◽  
Composites Manufacturing ◽  
Composite Molding ◽  
Particle Retention ◽  
Flow Through ◽  
Dual Scale

We present numerical simulation of particle filled resin flow through a fibrous media taking into account dual scale porosity in LCM (Liquid Composite Molding) processes. During the flow, a strong interaction between the particle motion and the fluid flow takes place at the porous medium wall or at the fiber bundle surface. A model is developed to describe the particle retention and filtration in the porous media. In this study, the Stokes-Darcy equation is solved to describe the resin flow in a mesoscopic scale. The particle retention mechanism is extensively studied taking into account the influences from such parameters as size and concentration of particles. The particle filled resin flow through a fibrous media simulation is performed to demonstrate the effect on the retention and filtration mechanism during the composites manufacturing by LCM processes.

Numerical analysis of viscous flow through fibrous media: a model for glomerular basement membrane permeability

1998 ◽  
Vol 274 (1) ◽  
pp. F223-F231 ◽  
Author(s):  
Matteo Palassini ◽  
Andrea Remuzzi
Keyword(s):  
Basement Membrane ◽  
Viscous Flow ◽  
Glomerular Basement Membrane ◽  
Three Dimensional ◽  
Periodic Array ◽  
Hydraulic Permeability ◽  
Fibrous Media ◽  
Ultrastructural Studies ◽  
Dimensionless Ratio ◽  
Flow Through

Viscous flow through fibrous media is characterized macroscopically by the Darcy permeability ( K D). The relationship between K D and the microscopic structure of the medium has been the subject of experimental and theoretical investigations. Calculations of K D based on the solution of the hydrodynamic flow at fiber scale exist in literature only for two-dimensional arrays of parallel fibers. We considered a fiber matrix consisting of a three-dimensional periodic array of cylindrical fibers with uniform radius ( r) and length connected in a tetrahedral structure. According to recent ultrastructural studies, this array of fibers can represent a model for the glomerular basement membrane (GBM). The Stokes flow through the periodic array was simulated using a Galerkin finite element method. The dimensionless ratio K* = K D/ r 2 was determined for values of the fractional solid volume (φ) in the range 0.005 ≤ φ ≤ 0.7. We compared our numerical results, summarized by an interpolating formula relating K* to φ, with previous theoretical determinations of hydraulic permeability in fibrous media. We found a good agreement with the Carman-Kozeny equation only for φ > 0.4. Among the other theoretical analysis considered, only that of Spielman and Goren ( Environ. Sci. Technol. 2: 279–287, 1968) gives satisfactory agreement in the whole range of φ considered. These results can be useful to model combined transport of water and macromolecules through the GBM for the estimation of the radius and length of extracellular protein fibrils.

Discovery of Antibacterial Agents Inhibiting the Energy-Coupling Factor (ECF) Transporters by Structure-Based Virtual Screening

2020 ◽  
Author(s):  
Eleonora Diamanti ◽  
Inda Setyawati ◽  
Spyridon Bousis ◽  
leticia mojas ◽  
lotteke Swier ◽  
...  
Keyword(s):  
Virtual Screening ◽  
Antibacterial Agents ◽  
Antimicrobial Agents ◽  
Energy Coupling ◽  
Coupling Factor ◽  
Design Synthesis ◽  
Screening Design ◽  
Starting Point ◽  
Wide Range ◽  
Vitamin Uptake

Here, we report on the virtual screening, design, synthesis and structure–activity relationships (SARs) of the first class of selective, antibacterial agents against the energy-coupling factor (ECF) transporters. The ECF transporters are a family of transmembrane proteins involved in the uptake of vitamins in a wide range of bacteria. Inhibition of the activity of these proteins could reduce the viability of pathogens that depend on vitamin uptake. Because of their central role in the metabolism of bacteria and their absence in humans, ECF transporters are novel potential antimicrobial targets to tackle infection. The hit compound’s metabolic and plasma stability, the potency (20, MIC Streptococcus pneumoniae = 2 µg/mL), the absence of cytotoxicity and a lack of resistance development under the conditions tested here suggest that this scaffold may represent a promising starting point for the development of novel antimicrobial agents with an unprecedented mechanism of action.<br>

scholarly journals Consumer Neuroscience Techniques in Advertising Research: A Bibliometric Citation Analysis

2021 ◽  
Vol 13 (3) ◽  
pp. 1589
Author(s):  
Juan Sánchez-Fernández ◽  
Luis-Alberto Casado-Aranda ◽  
Ana-Belén Bastidas-Manzano
Keyword(s):  
Self Report ◽  
Future Research ◽  
Complex Nature ◽  
Clear Understanding ◽  
Continuous Growth ◽  
Main Research ◽  
Consumer Neuroscience ◽  
Starting Point ◽  
Wide Range ◽  
Performance Analysis Tools

The limitations of self-report techniques (i.e., questionnaires or surveys) in measuring consumer response to advertising stimuli have necessitated more objective and accurate tools from the fields of neuroscience and psychology for the study of consumer behavior, resulting in the creation of consumer neuroscience. This recent marketing sub-field stems from a wide range of disciplines and applies multiple types of techniques to diverse advertising subdomains (e.g., advertising constructs, media elements, or prediction strategies). Due to its complex nature and continuous growth, this area of research calls for a clear understanding of its evolution, current scope, and potential domains in the field of advertising. Thus, this current research is among the first to apply a bibliometric approach to clarify the main research streams analyzing advertising persuasion using neuroimaging. Particularly, this paper combines a comprehensive review with performance analysis tools of 203 papers published between 1986 and 2019 in outlets indexed by the ISI Web of Science database. Our findings describe the research tools, journals, and themes that are worth considering in future research. The current study also provides an agenda for future research and therefore constitutes a starting point for advertising academics and professionals intending to use neuroimaging techniques.

scholarly journals Universal mobility characteristics of graphene originating from charge scattering by ionised impurities

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jonathan H. Gosling ◽  
Oleg Makarovsky ◽  
Feiran Wang ◽  
Nathan D. Cottam ◽  
Mark T. Greenaway ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carrier Density ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Analytical Models ◽  
Pristine Graphene ◽  
High Electron ◽  
Boltzmann Transport ◽  
Transport Parameters ◽  
Wide Range

AbstractPristine graphene and graphene-based heterostructures can exhibit exceptionally high electron mobility if their surface contains few electron-scattering impurities. Mobility directly influences electrical conductivity and its dependence on the carrier density. But linking these key transport parameters remains a challenging task for both theorists and experimentalists. Here, we report numerical and analytical models of carrier transport in graphene, which reveal a universal connection between graphene’s carrier mobility and the variation of its electrical conductivity with carrier density. Our model of graphene conductivity is based on a convolution of carrier density and its uncertainty, which is verified by numerical solution of the Boltzmann transport equation including the effects of charged impurity scattering and optical phonons on the carrier mobility. This model reproduces, explains, and unifies experimental mobility and conductivity data from a wide range of samples and provides a way to predict a priori all key transport parameters of graphene devices. Our results open a route for controlling the transport properties of graphene by doping and for engineering the properties of 2D materials and heterostructures.

Krypton 85 myocardial blood flow: precordial scintillation versus coronary sinus sampling

1965 ◽  
Vol 209 (4) ◽  
pp. 705-710 ◽  
Author(s):  
Michael D. Klein ◽  
Lawrence S. Cohen ◽  
Richard Gorlin
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Coronary Sinus ◽  
Human Subjects ◽  
Radioactive Decay ◽  
Empirical Correction ◽  
Wide Range ◽  
Actual Flow ◽  
Flow Through ◽  
High Degree

Myocardial blood flow in human subjects was assessed by comparative simultaneous measurement of krypton 85 radioactive decay from coronary sinus and precordial scintillation. Empirical correction of postclearance background from precordial curves yielded a high degree of correlation between flows derived from the two sampling sites (r = .889, P < .001). Comparison of left and right coronary flows in nine subjects revealed similarity in flow through the two vessels over a wide range of actual flow values (r = .945, P < .001).

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