Abstract
The stability of natural convection in a fluid-saturated vertical anisotropic porous layer is investigated. The vertical rigid walls of the porous layer are maintained at different constant temperatures, and anisotropy in both permeability and thermal diffusivity is considered. The flow in the porous medium is described by the Lapwood–Brinkman model, and the stability of the basic flow is analysed numerically using Chebyshev collocation method. The presence of inertia is to inflict instability on the system and in the absence of which the system is always found to be stable. The mechanical and thermal anisotropies exhibit opposing contributions on the stability characteristics of the system. The mode of instability is interdependent on the values of Prandtl number and thermal anisotropy parameter, while it remains unaltered with the mechanical anisotropy parameter. The effect of increasing Prandtl and Darcy numbers shows a destabilizing effect on the system. Besides, simulations of secondary flow and energy spectrum have been analysed for various values of physical parameters at the critical state.
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Abbreviations
- a :
-
Vertical wave number
- c :
-
Wave speed
- \(c_\mathrm{r}\) :
-
Phase velocity
- \(c_i \) :
-
Growth rate
- Da :
-
Darcy number
- \(E_\mathrm{b} , E_\mathrm{d} , E_\mathrm{D} , E_\mathrm{s}\) :
-
Disturbance kinetic energies
- \(\vec {g}\) :
-
Acceleration due to gravity
- G :
-
Grashof number
- h :
-
Half-width of the porous layer
- \(\hat{{i}}\) :
-
Unit vector in x-direction
- \(\hat{{k}}\) :
-
Unit vector in z-direction
- \(\underset{{\thicksim }}{K}\) :
-
Second-order permeability tensor
- \({K}_{x}\) :
-
Transverse component of the permeability
- \(K_z\) :
-
Longitudinal component of the permeability
- \(K_1\) :
-
Mechanical anisotropy parameter
- p :
-
Pressure
- Pr :
-
Prandtl number
- \(\vec {q}=(u,v,w)\) :
-
Velocity vector
- t :
-
Time
- T :
-
Temperature
- \(T_\mathrm{c}, T_\mathrm{d}\) :
-
Disturbance thermal energies
- \(T_1\) :
-
Temperature of the left boundary
- \(T_2\) :
-
Temperature of the right boundary
- \(W_\mathrm{b}\) :
-
Basic velocity
- \(\left( {x,y,z} \right) \) :
-
Cartesian co-ordinates
- \(\alpha \) :
-
Volumetric thermal expansion coefficient
- \(\beta \) :
-
Temperature gradient
- \(\chi \) :
-
Ratio of heat capacities
- \(\varphi _\mathrm{p}\) :
-
Porosity of the porous medium
- \(\underset{{\thicksim }}{\kappa }\) :
-
Thermal diffusivity tensor
- \(\kappa _x \) :
-
Transverse component of the thermal diffusivity
- \(\kappa _z \) :
-
Longitudinal component of the thermal diffusivity
- \(\kappa _1 \) :
-
Thermal anisotropy parameter
- \(\mu \) :
-
Fluid viscosity
- \(\mu _\mathrm{e} \) :
-
Effective fluid viscosity
- \(\nu \) :
-
Kinematic viscosity
- \(\theta \) :
-
Amplitude of perturbed temperature
- \(\rho \) :
-
Fluid density
- \(\rho _0 \) :
-
Reference density at \(T_0 \)
- \(\psi \) :
-
Stream function
- \(\Psi \) :
-
Amplitude of vertical component of perturbed velocity
References
Nield, D.A., Bejan, A.: Convection in Porous Media. Springer, New York (2013)
Straughan, B.: The Energy Method, Stability, and Nonlinear Convection. Springer, New York (2004)
Straughan, B.: Stability and Wave Motion in Porous Media, vol. 165. Springer, Heidelberg (2008)
Turcotte, D.L., Schubert, G.: Geodynamics, 3rd edn. Cambridge University Press, Cambridge (2014)
Castinel, G., Combarnous, M.: Natural convection in an anisotropic porous layer. Int. Chem. Eng. 17, 605–613 (1977)
Epherre, J.F.: Criterion for the appearance of natural convection in an anisotropic porous layer. Int. Chem. Eng. 17, 615–616 (1977)
McKibbin, R., Tyvand, P.A.: Anisotropic modelling of thermal convection in multilayered porous media. J. Fluid Mech. 118, 315–339 (1982)
Tyvand, P.A., Storesletten, L.: Onset of convection in an anisotropic porous medium with oblique principal axis. J. Fluid Mech. 226, 371–382 (1991)
Straughan, B., Walker, D.W.: Anisotropic porous penetrative convection. Proc. R. Soc. Lond. A 452, 97–115 (1996)
Payne, L.E., Rodrigues, J.F., Straughan, B.: Effect of anisotropic permeability on Darcy’s law. Math. Methods Appl. Sci. 24, 427–438 (2001)
Rees, D.A.S., Postelnicu, A.: The onset of convection in an inclined anisotropic porous layer. Int. J. Heat Mass Transf. 44, 4127–4138 (2001)
Khalili, A., Shivakumara, I.S., Huettel, M.: Effects of throughflow and internal heat generation on convective instabilities in an anisotropic porous layer. J. Porous Med. 5, 187–198 (2002)
Storesletten, L.: Effects of anisotropy on convection in horizontal and inclined porous layers. Emerg. Tech. Techn. Por. Med., pp. 285–306. Kluwer Academic, Dordrecht (2004)
Capone, F., Gentile, M., Hill, A.A.: Anisotropy and symmetry in porous media convection. Acta Mech. 208, 205–214 (2009)
Capone, F., Gentile, M., Hill, A.A.: Penetrative convection in anisotropic porous media with variable permeability. Acta Mech. 216, 49–58 (2011)
Capone, F., Gentile, M., Hill, A.A.: Convection problems in anisotropic porous media with nonhomogeneous porosity and thermal diffusivity. Acta Appl. Math. 122, 85–91 (2012)
Shiina, Y., Hishida, M.: Critical Rayleigh number of natural convection in high porosity anisotropic horizontal porous layers. Int. J. Heat Mass Transf. 53, 1507–1513 (2010)
Haddad, S.A.M.: Thermal convection in a Darcy porous medium with anisotropic spatially varying permeability. Acta Appl. Math. 132, 359–370 (2014)
Burns, P.J., Chow, L.C., Tien, C.L.: Convection in a vertical slot filled with porous insulation. Int. J. Heat Mass Transf. 20, 919–926 (1977)
Poulikakos, D., Bejan, A.: Natural convection in vertically and horizontally layered porous media heated from the side. Int. J. Heat Mass Transf. 26, 1805–1814 (1983)
Lai, F.C., Kulacki, F.A.: Natural convection across a vertical layered porous cavity. Int. J. Heat Mass Transf. 31, 1247–1260 (1988)
Ni, J., Beckermann, C.: Natural convection in a vertical enclosure filled with anisotropic porous media. J. Heat Transf. 113, 1033–1037 (1993)
Degan, G., Vasseur, P., Bilgen, E.: Convective heat transfer in a vertical anisotropic porous layer. Int. J. Heat Mass Transf. 38, 1975–1987 (1995)
Degan, G., Vasseur, P.: Aiding mixed convection through a vertical anisotropic porous channel with oblique principal axes. Int. J. Eng. Sci. 40, 193–209 (2002)
Gill, A.E.: A proof that convection in a porous vertical slab is stable. J. Fluid Mech. 35, 545–547 (1969)
Hong, J.T., Tien, C.L., Kaviany, M.: Non-Darcian effects on vertical plate natural convection in porous media with high porosities. Int. J. Heat Mass Transf. 28, 2149–2157 (1985)
Kwok, L.P., Chen, C.F.: Stability of thermal convection in a vertical porous layer. J. Heat Transf. 109, 889–893 (1987)
Qin, Y., Kaloni, P.N.: A nonlinear stability problem of convection in a porous vertical slab. Phys. Fluids A 5, 2067–2069 (1993)
Shankar, B.M., Kumar, J., Shivakumara, I.S.: Effect of horizontal alternating current electric field on the stability of natural convection in a dielectric fluid saturated vertical porous layer. J. Heat Transf. 137, 042501-1–042501-9 (2015)
Shankar B.M., Kumar, J., Shivakumara, I.S. (2016) Stability of natural convection in a vertical layer of Brinkman porous medium. Acta Mech. doi:10.1007/s00707-016-1690-6
Canuto, C., Hussaini, M., Quarteroni, A., Zang, T.A.: Spectral Methods in Fluid Dynamics. Springer, New York (1988)
Shankar, B.M., Kumar, J., Shivakumara, I.S.: Stability of natural convection in a vertical couple stress fluid layer. Int. J. Heat Mass Transf. 78, 447–459 (2014)
Su, Y.C., Chung, J.N.: Linear stability analysis of mixed-convection flow in a vertical pipe. J. Fluid Mech. 422, 141–166 (2000)
McBain, G.D., Armfield, S.W.: Natural convection in a vertical slot: accurate solution of the linear stability equations. ANZIAM J. 45, 92–105 (2004)
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Shankar, B.M., Kumar, J. & Shivakumara, I.S. Boundary and inertia effects on the stability of natural convection in a vertical layer of an anisotropic Lapwood–Brinkman porous medium. Acta Mech 228, 2269–2282 (2017). https://doi.org/10.1007/s00707-017-1831-6
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DOI: https://doi.org/10.1007/s00707-017-1831-6