Local thermal nonequilibrium conjugate natural convection of nano-encapsulated phase change particles in a partially porous enclosure

2020 ◽  
Author(s):  
S. A. M. Mehryan ◽  
Muneer Ismael ◽  
Mohammad Ghalambaz
Keyword(s):  
Natural Convection ◽  
Phase Change ◽  
Thermal Nonequilibrium ◽  
Conjugate Natural Convection ◽  
Local Thermal Nonequilibrium ◽  
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.

CONJUGATE NATURAL CONVECTION IN AN INCLINED SQUARE POROUS ENCLOSURE WITH FINITE WALL THICKNESS AND PARTIALLY HEATED FROM ITS LEFT SIDEWALL

2016 ◽  
Vol 47 (4) ◽  
pp. 383-402 ◽  
Author(s):  
Sameh E. Ahmed ◽  
Ahmed Kadhim Hussein ◽  
M. M. Abd El-Aziz ◽  
Sivanandam Sivasankaran
Keyword(s):  
Natural Convection ◽  
Wall Thickness ◽  
Conjugate Natural Convection ◽  
Porous Enclosure
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