THERMAL INSTABILITY OF OLDROYDIAN VISCO-ELASTIC NANOFLUID IN A POROUS MEDIUM FOR MORE REALISTIC BOUNDARY CONDITIONS

2020 ◽  
Author(s):  
Ramesh Chand ◽  
S.K. Kango
Keyword(s):  
Porous Medium ◽  
Boundary Conditions ◽  
Thermal Instability ◽  
Realistic Boundary Conditions

Brinkman ferroconvection

2017 ◽  
Vol 13 (3) ◽  
pp. 366-376
Author(s):  
M. Ravisha ◽  
I.S. Shivakumara ◽  
Gangadhara Reddy R.
Keyword(s):  
Porous Medium ◽  
Eigenvalue Problem ◽  
Boundary Conditions ◽  
Galerkin Method ◽  
Shooting Method ◽  
Critical Rayleigh Number ◽  
Content Type ◽  
Vertical Heterogeneity ◽  
Ferromagnetic Convection ◽  
Realistic Boundary Conditions

Purpose The simultaneous effects of local thermal non-equilibrium (LTNE) and vertical heterogeneity in permeability on the onset of ferromagnetic convection in a Brinkman porous medium are analyzed in the presence of a uniform vertical magnetic field. The eigenvalue problem is solved numerically using shooting method for isothermal rigid-ferromagnetic boundaries for various forms of vertically stratified permeability function Γ(z). The effect of vertically stratified permeability is found to either hasten or delay the onset of ferromagnetic convection. The deviation in the critical Rayleigh number between different forms of Γ(z) is found to be not so significant with an increase in the Darcy number. It is observed that the general quadratic variation of Γ(z) has more destabilizing effect on the system when compared to the constant permeability porous medium case. Besides, the influence of LTNE and magnetic parameters on the criterion for the onset of ferromagnetic convection has been assessed in detail. The paper aims to discuss these issues. Design/methodology/approach Ferroconvection in a porous medium has been analyzed considering heterogeneity in the permeability of the porous medium. The resulting eigenvalue problem has been solved numerically using shooting method as well as Galerkin method for realistic boundary conditions. Findings The novelty of the present study lies in understanding the effect of heterogeneity in the permeability of the porous medium on control of ferroconvection in a porous medium. In analyzing the problem, realistic boundary conditions are considered and the resulting eigenvalue problem is solved numerically using shooting method as well as Galerkin method. Originality/value Control of ferroconvection in a porous medium is an important feature in heat transfer-related problems and many mechanisms are being used to understand this aspect in the literature. The novelty of the present study lies in recognizing the effect of heterogeneity in the permeability of the porous medium on control of ferroconvection. This fact has been analyzed in detail for various forms of heterogeneity functions using numerical techniques by considering realistic boundary conditions.

scholarly journals The Importance of Nanoparticles Addition in a Base Fluid Flow through a Porous Medium

2013 ◽  
Vol 8-9 ◽  
pp. 225-234
Author(s):  
Dalia Sabina Cimpean
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Boundary Conditions ◽  
Mixed Convection ◽  
Mathematical Models ◽  
Base Fluid ◽  
Porous Matrix ◽  
Fluid Properties ◽  
Flow Through ◽  
Energy Equations

The present study is focused on the mixed convection fluid flow through a porous medium, when a different amount of nanoparticles is added in the base fluid. The nanofluid saturates the porous matrix and different situations of the flow between two walls are presented and discussed. Alternatively mathematical models are presented and discussed. A solution of a system which contains the momentum, Darcy and energy equations, together with the boundary conditions involved, is given. The behavior of different nanofluids, such thatAu-water, Ag-waterandFe-wateris graphically illustrated and compared with the previous results.The research target is to observe the substantial increase of the thermophysical fluid properties, when the porous medium issaturated by a nanofluid instead of a classical Newtonian fluid.

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