Thermal instability in a rotating porous layer saturated by a non-Newtonian nanofluid with thermal conductivity and viscosity variation

2013 ◽  
Vol 16 (1-2) ◽  
pp. 425-440 ◽  
Author(s):  
Dhananjay Yadav ◽  
R. Bhargava ◽  
G. S. Agrawal ◽  
Nirmal Yadav ◽  
Jinho Lee ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Porous Layer ◽  
Thermal Instability ◽  
Viscosity Variation ◽  
Conductivity And Viscosity Variation

Thermal Instability of a Fluid-Saturated Porous Medium Bounded by Thin Fluid Layers

1987 ◽  
Vol 109 (3) ◽  
pp. 677-682 ◽  
Author(s):  
G. Pillatsis ◽  
M. E. Taslim ◽  
U. Narusawa
Keyword(s):  
Porous Medium ◽  
Porous Layer ◽  
Thermal Instability ◽  
Numerical Solutions ◽  
Fluid Layer ◽  
Critical Rayleigh Number ◽  
Convective Motion ◽  
Wave Number ◽  
Thermal Conductivity Ratio ◽  
Fluid Layers

A linear stability analysis is performed for a horizontal Darcy porous layer of depth 2dm sandwiched between two fluid layers of depth d (each) with the top and bottom boundaries being dynamically free and kept at fixed temperatures. The Beavers–Joseph condition is employed as one of the interfacial boundary conditions between the fluid and the porous layer. The critical Rayleigh number and the horizontal wave number for the onset of convective motion depend on the following four nondimensional parameters: dˆ ( = dm/d, the depth ratio), δ ( = K/dm with K being the permeability of the porous medium), α (the proportionality constant in the Beavers–Joseph condition), and k/km (the thermal conductivity ratio). In order to analyze the effect of these parameters on the stability condition, a set of numerical solutions is obtained in terms of a convergent series for the respective layers, for the case in which the thickness of the porous layer is much greater than that of the fluid layer. A comparison of this study with the previously obtained exact solution for the case of constant heat flux boundaries is made to illustrate quantitative effects of the interfacial and the top/bottom boundaries on the thermal instability of a combined system of porous and fluid layers.

Assessment of Thermal Non-Equilibrium Condition on Heat Transfer through a Channel Lined with Porous Media – Constant Wall Temperature

2011 ◽  
Vol 312-315 ◽  
pp. 33-38
Author(s):  
M. Abkar ◽  
P. Forooghi ◽  
A. Abbassi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Porous Layer ◽  
Biot Number ◽  
Equilibrium Condition ◽  
Solid Phase ◽  
Local Thermal Equilibrium ◽  
Thermal Conductivity Ratio ◽  
Constant Wall Temperature ◽  
Non Equilibrium

In this paper, forced convection in a channel lined with a porous layer is investigated. The main goal is to assess the effect of local thermal non-equilibrium condition on overall heat transfer in the channel. The effects of thermal conductivity of solid and thickness of porous layer are also studied. Flow assumed to be laminar and fully developed. The Brinkman-Forchheimer model for flow as well as the two equation energy model is used. The results showed that when the problem tends to local thermal equilibrium condition, heat transfer is enhanced due to heat conduction through solid phase. Another factor, which can facilitate the heat transfer, is the increase of the thermal conductivity of solid material. This trend is sensitive to the thickness of porous layer and modified Biot number, which is a measure (criterion) of local fluid to solid heat transfer. As thickness and modified Biot number increase, the Nusselt number becomes more sensitive to the thermal conductivity ratio.

Thermal Instability of a Power-Law Fluid Flowing in a Horizontal Porous Layer with an Open Boundary: A Two-Dimensional Analysis

2017 ◽  
Vol 118 (3) ◽  
pp. 449-471 ◽  
Author(s):  
M. Celli ◽  
A. Barletta ◽  
S. Longo ◽  
L. Chiapponi ◽  
V. Ciriello ◽  
...  
Keyword(s):  
Dimensional Analysis ◽  
Porous Layer ◽  
Power Law ◽  
Thermal Instability ◽  
Open Boundary ◽  
Two Dimensional ◽  
Power Law Fluid
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