Entropy Generation for Thermal Nonequilibrium Natural Convection with a Non-Darcy Flow Model in a Porous Enclosure Filled with a Heat-Generating Solid Phase

2007 ◽  
Vol 10 (3) ◽  
pp. 261-275 ◽  
Author(s):  
A. Cihat Baytas
Keyword(s):  
Natural Convection ◽  
Entropy Generation ◽  
Flow Model ◽  
Solid Phase ◽  
Darcy Flow ◽  
Thermal Nonequilibrium ◽  
Porous Enclosure

Magnetohydrodynamic natural convection of hybrid nanofluid in a porous enclosure: numerical analysis of the entropy generation

2020 ◽  
Vol 141 (5) ◽  
pp. 1981-1992 ◽  
Author(s):  
Zaim Abdel-Nour ◽  
Abderrahmane Aissa ◽  
Fateh Mebarek-Oudina ◽  
A. M. Rashad ◽  
Hafiz Muhammad Ali ◽  
...  
Keyword(s):  
Natural Convection ◽  
Numerical Analysis ◽  
Entropy Generation ◽  
Hybrid Nanofluid ◽  
Porous Enclosure

scholarly journals Effect of Local Thermal Nonequilibrium on the Stability of Natural Convection in an Oldroyd-B Fluid Saturated Vertical Porous Layer

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
B. M. Shankar ◽  
I. S. Shivakumara
Keyword(s):  
Natural Convection ◽  
Solid Phase ◽  
Viscoelastic Fluids ◽  
Maxwell Fluid ◽  
Base Flow ◽  
Temperature Fields ◽  
Thermal Nonequilibrium ◽  
Interphase Heat Transfer ◽  
Local Thermal Nonequilibrium ◽  
The Stability

The effect of local thermal nonequilibrium (LTNE) on the stability of natural convection in a vertical porous slab saturated by an Oldroyd-B fluid is investigated. The vertical walls of the slab are impermeable and maintained at constant but different temperatures. A two-field model that represents the fluid and solid phase temperature fields separately is used for heat transport equation. The resulting stability eigenvalue problem is solved numerically using Chebyshev collocation method as the energy stability analysis becomes ineffective in deciding the stability of the system. Despite the basic state remains the same for Newtonian and viscoelastic fluids, it is observed that the base flow is unstable for viscoelastic fluids and this result is qualitatively different from Newtonian fluids. The results for Maxwell fluid are delineated as a particular case from the present study. It is found that the viscoelasticity has both stabilizing and destabilizing influence on the flow. Increase in the value of interphase heat transfer coefficient Ht, strain retardation parameter Λ2 and diffusivity ratio α portray stabilizing influence on the system while increasing stress relaxation parameter Λ1 and porosity-modified conductivity ratio γ exhibit an opposite trend.

Numerical investigation of natural convection in an inclined porous enclosure using non-Darcian flow model

2019 ◽  
Vol 30 (4) ◽  
pp. 1881-1897
Author(s):  
Ibrahim Atiya Mohamed
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Nusselt Number ◽  
Natural Convection ◽  
Flow Model ◽  
Boundary Surface ◽  
Content Type ◽  
Inertia Effects ◽  
Porous Cavity ◽  
Porous Enclosure

Purpose A thoroughly literature review reveals that considerable attention have been given only to the two common cases, i.e. enclosure heated from below and heated from the side. For the inclined layer, on the other hand, the numbers of investigations are relatively small. Therefore, this paper aims to investigate the natural convective heat transfer in an inclined porous cavity using non-Darcian flow model, including the boundary surface and inertia effects. Design/methodology/approach The flow characteristics have been assumed to be two-dimensional, steady, incompressible flow, whereas the properties of porous media have been considered to be homogeneous and isotropic properties solid matrix. The non-Darcian flow model, including the boundary surface and inertia effects, has been numerically solved using finite difference method. Findings The initiation of multicellular flow and counter-rotating cell are strongly dependent on the aspect ratio A and the inclination angle θ. The orientation of the porous cavity, for a given Ra*, Fs/Pr* and A, has a significant effect on the heat transfer rate. The results also indicated that A has a dominant effect on the Nusselt number. The Nusselt number is strongly dependent on the Ra*, Fs/Pr*, A and θ. Therefore, operating conditions and geometry of the porous enclosure are required to be properly designed to achieve the desired objective. Originality/value The developed model can reveal the non-Darcian effects on the fluid flow and heat transfer in inclined porous media under natural convection case.

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