scholarly journals Thermosolutal Convection in a Porous Medium Cavity Subjected to Heat and Mass Flux: A Discrete Fracture Effect

2020 ◽  
Vol 12 (1) ◽  
pp. 86-104
Author(s):  
Zakaria Aouf ◽  
Chakib Seladji
Keyword(s):  
Porous Medium ◽  
Soret Effect ◽  
Heterogeneous Porous Media ◽  
Separation Process ◽  
Thermosolutal Convection ◽  
Cold Wall ◽  
Positive Role ◽  
Industrial Activities ◽  
Discrete Fracture ◽  
The One

AbstractSpecies separation in heterogeneous porous media is a field of interest of many industrial activities. In our investigation, the effect of a single discrete fracture on the thermosolutal convection coupled with the Soret effect have been analyzed. The main results show that the fracture can greatly affect the behavior of the thermogravitational flow and might play a positive role to the separation caused by the Soret effect. Furthermore, the fracture tilted to the cold wall causes a large separation compared to the one tilted to the hot wall with the same angle. Therefore, the separation process could be greatly improved.

Numerical Analysis of Ludwig-Soret Effect of One Binary Mixture and Two Ternary Mixtures in an Al2O3 Porous Cavity

2006 ◽  
Author(s):  
T. J. Jaber ◽  
M. Z. Saghir
Keyword(s):  
Porous Medium ◽  
Steady State ◽  
Numerical Analysis ◽  
Binary Mixture ◽  
Ternary Mixture ◽  
Soret Effect ◽  
Ternary Mixtures ◽  
Thermosolutal Convection ◽  
Left Wall ◽  
Porous Cavity

A cavity of 10 mm in width, 10 mm in height, and 32.1 mm in horizontal length filled with Al2O3 porous medium designed in Pau project to investigate thermal diffusion phenomena, or Ludwig-Soret effect. A lateral heating condition was applied with 10 °C at the left wall and 50 °C at the right wall. The thermosolutal convection of a binary mixture of water-ethanol at 75.0 MPa pressure, a ternary mixture with methane, n-butane, and n-dodecan at 35.0 MPa pressure, and a ternary mixture of n-dodecane, isobutylbenzene, and tetrahydonaphthalene at atmosphere pressure inside the Al2O3 porous medium cavity were numerically investigated. The thermal conductivity and the permeability of Al2O3 porous medium on the Ludwig-Soret effect were analyzed, the former had little influence, but the later had strong impact on the compositional separation at the steady state of thermosolutal convection, which were analyzed globally with separation ratio. The distributions of component mole fraction(s) on the horizontal and vertical lines in the center of the porous cavity were also shown to study the details of the compositional separation at the steady state of thermosolutal convection. Recommendations are made for the experimental design based on the results of numerical analysis

Thermosolutal convection of a nanofluid in ∧-shaped cavity saturated by a porous medium

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdelraheem M. Aly ◽  
Zehba Raizah
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Circular Cylinder ◽  
Volume Fraction ◽  
Heterogeneous Porous Media ◽  
Thermosolutal Convection ◽  
Content Type ◽  
Solutal Convection ◽  
Buoyancy Ratio ◽  
Darcy Parameter

Purpose The purpose of this study is to simulate the thermo-solutal convection resulting from a circular cylinder hanging in a rod inside a ∧-shaped cavity. Design/methodology/approach The two dimensional ∧-shaped cavity is filled by Al2O3-water nanofluid and saturated by three different levels of heterogeneous porous media. An incompressible smoothed particle hydrodynamics (ISPH) method is adopted to solve the governing equations of the present problem. The present simulations have been performed for the alteration of buoyancy ratio (−2≤N≤2), radius of a circular cylinder (0.05≤Rc≤0.3), a height of a rod (0.1≤Lh≤0.4), Darcy parameter (10−3≤Da≤10−5), Lewis number (1≤Le≤40), solid volume fraction (0≤ϕ≤0.06), porous levels (0≤η1=η2≤1.5)and various boundary-wall conditions. Findings The performed numerical simulations indicated the importance of embedded shapes on the distributions of temperature, concentration and velocity fields inside ∧-shaped cavity. Increasing buoyancy ratio parameter enhances thermo-solutal convection and nanofluid velocity. Adiabatic conditions of the vertical-walls of ∧-shaped cavity augment the distributions of the temperature and concentration. Regardless the Darcy parameter, a homogeneous porous medium gives the lowest values of a nanofluid velocity. Originality/value ISPH method is used to simulate thermo-solutal convection of a nanofluid inside a novel ∧-shaped cavity containing a novel embedded shape and heterogeneous porous media.

Numerical Analysis of Thermal-Solutal Convection in Heterogeneous Porous Media

2005 ◽  
Vol 73 (1) ◽  
pp. 21-25 ◽  
Author(s):  
Charles-Guobing Jiang ◽  
M. Ziad Saghir ◽  
M. Kawaji
Keyword(s):  
Porous Media ◽  
Thermal Diffusion ◽  
Soret Effect ◽  
Heterogeneous Porous Media ◽  
Soret Coefficient ◽  
Solutal Convection ◽  
Coefficient Distribution ◽  
Separation Ratio ◽  
Diffusion In Porous Media ◽  
Vertical Cavity

Thermal diffusion, or Soret effect, in porous media is mathematically modeled with the Firoozabadi model based on non-equilibrium thermodynamics. The Soret effect in a binary mixture is investigated in a vertical cavity with heterogeneous permeability, where natural convection can occur. The thermo solutal convection with heterogeneous permeability was studied in terms of flow pattern, concentration distribution, component separation ratio, and Soret coefficient distribution. A consistent analysis was conducted and it is concluded that the Soret coefficient of thermal diffusion in porous media strongly depends on the heterogeneity of permeability.

scholarly journals Signaling pathways have an inherent need for noise to acquire information

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Eugenio Azpeitia ◽  
Eugenio P. Balanzario ◽  
Andreas Wagner
Keyword(s):  
Signaling Pathways ◽  
Information Acquisition ◽  
Cellular Level ◽  
Kinetic Properties ◽  
Positive Role ◽  
Binding Interactions ◽  
Reversible Binding ◽  
Wide Range ◽  
The One ◽  
Parameter Values

Abstract Background All living systems acquire information about their environment. At the cellular level, they do so through signaling pathways. Such pathways rely on reversible binding interactions between molecules that detect and transmit the presence of an extracellular cue or signal to the cell’s interior. These interactions are inherently stochastic and thus noisy. On the one hand, noise can cause a signaling pathway to produce the same response for different stimuli, which reduces the amount of information a pathway acquires. On the other hand, in processes such as stochastic resonance, noise can improve the detection of weak stimuli and thus the acquisition of information. It is not clear whether the kinetic parameters that determine a pathway’s operation cause noise to reduce or increase the acquisition of information. Results We analyze how the kinetic properties of the reversible binding interactions used by signaling pathways affect the relationship between noise, the response to a signal, and information acquisition. Our results show that, under a wide range of biologically sensible parameter values, a noisy dynamic of reversible binding interactions is necessary to produce distinct responses to different stimuli. As a consequence, noise is indispensable for the acquisition of information in signaling pathways. Conclusions Our observations go beyond previous work by showing that noise plays a positive role in signaling pathways, demonstrating that noise is essential when such pathways acquire information.

Two-Phase Boundary Layer Treatment for Subcooled Free-Convection Film Boiling Around a Body of Arbitrary Shape in a Porous Medium

1987 ◽  
Vol 109 (4) ◽  
pp. 997-1002 ◽  
Author(s):  
A. Nakayama ◽  
H. Koyama ◽  
F. Kuwahara
Keyword(s):  
Boundary Layer ◽  
Porous Medium ◽  
Free Convection ◽  
Phase Boundary ◽  
Flat Plate ◽  
Arbitrary Shape ◽  
Film Boiling ◽  
Two Phase ◽  
The One ◽  
Axisymmetric Bodies

The two-phase boundary layer theory was adopted to investigate subcooled free-convection film boiling over a body of arbitrary shape embedded in a porous medium. A general similarity variable which accounts for the geometric effect on the boundary layer length scale was introduced to treat the problem once for all possible two-dimensional and axisymmetric bodies. By virtue of this generalized transformation, the set of governing equations and boundary conditions for an arbitrary shape reduces into the one for a vertical flat plate already solved by Cheng and Verma. Thus, the numerical values furnished for a flat plate may readily be tranlsated for any particular body configuration of concern. Furthermore, an explicit Nusselt number expression in terms of the parameters associated with the degrees of subcooling and superheating has been established upon considering physical limiting conditions.

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