The aim of this study is the analysis of the onset conditions for the thermal instability in a fluid saturated porous medium. The investigation refers to an infinitely wide horizontal porous layer with vertical heterogeneity, such that the lower plane boundary is impermeable and thermally insulated (adiabatic). The temperature distribution on the upper plane boundary is assumed to be prescribed and linearly varying in the horizontal direction. It is shown that these boundary conditions are compatible with a buoyancy-induced parallel-flow solution such that the temperature gradient is inclined with respect to the vertical direction. The basic parallel flow is perturbed by small–amplitude roll disturbances, so that a linear analysis of the neutral stability is carried out. The local balance equations for the disturbances are solved numerically. The critical conditions for the onset of convection are determined.

References

1.
Simmons
,
C. T.
,
Fenstemaker
,
T. R.
, and
Sharp
,
J. M.
, 2001, “
Variable–Density Groundwater Flow and Solute Transport in Heterogeneous Porous Media: Approaches, Resolutions and Future Challenges
,”
J. Contam. Hydrol.
,
52
, pp.
245
275
.
2.
Nield
,
D. A.
, and
Bejan
,
A.
, 2006,
Convection in Porous Media
, 3rd ed.,
Springer–Verlag
,
New York.
3.
Braester
,
C.
, and
Vadasz
,
P.
, 1993, “
The Effect of a Weak Heterogeneity of a Porous Medium on Natural Convection
,”
J. Fluid Mech.
,
254
, pp.
345
362
.
4.
Sundaravadivelu
,
K.
, and
Tso
,
C. P.
, 2003, “
Influence of Viscosity Variations on the Forced Convection Flow Through Two Types of Heterogeneous Porous Media With Isoflux Boundary Condition
,”
Int. J. Heat Mass Transfer
,
46
, pp.
2329
2339
.
5.
Shivakumara
,
I. S.
,
Lee
,
J.
,
Vajravelu
,
K.
, and
Mamatha
,
A. L.
, 2011, “
Effects of Thermal Nonequilibrium and Non-uniform Temperature Gradients on the Onset of Convection in a Heterogeneous Porous Medium
,”
Int. Commun. in Heat Mass Transfer
,
38
, pp.
906
910
.
6.
McKibbin
,
R.
, and
O’Sullivan
,
M. J.
, 1981, “
Heat Transfer in a Layered Porous Medium Heated From Below
,”
J. Fluid Mech.
,
111
, pp.
141
173
.
7.
McKibbin
,
R.
, and
Tyvand
,
P. A.
, 1983, “
Thermal Convection in a Porous Medium Composed of Alternating Thick and Thin Layers
,”
Int. J. Heat Mass Transfer
,
26
, pp.
761
780
.
8.
Poulikakos
,
D.
, and
Bejan
,
A.
, 1983, “
Natural Convection in Vertically and Horizontally Layered Porous Media Heated From the Side
,”
Int. J. Heat Mass Transfer
,
26
, pp.
1805
1814
.
9.
Gjerde
,
K. M.
, and
Tyvand
,
P. A.
, 1984, “
Thermal Convection in a Porous Medium With Continuous Periodic Stratification
,”
Int. J. Heat Mass Transfer
,
27
, pp.
2289
2295
.
10.
Hong
,
J. T.
,
Yamada
,
Y.
, and
Tien
,
C. L.
, 1987, “
Effects of Non–Darcian and Nonuniform Porosity on Vertical Plate Natural Convection in Porous Media
,”
Trans. ASME J. Heat Transfer
,
109
, pp.
356
362
.
11.
Lai
,
F. C.
, and
Kulacki
,
F. A.
, 1988, “
Natural Convection Across a Vertical Layered Porous Cavity
,”
Int. J. Heat Mass Transfer
,
31
, pp.
1247
1260
.
12.
Nield
,
D. A.
, and
Kuznetsov
,
A. V.
, 2000, “
Effects of Heterogeneity in Forced Convection in a Porous Medium: Parallel Plate Channel or Circular Duct
,”
Int. J. Heat Mass Transfer
,
43
, pp.
4119
4134
.
13.
Nield
,
D. A.
, and
Kuznetsov
,
A. V.
, 2001, “
Effects of Heterogeneity in Forced Convection in a Porous Medium: Parallel Plate Channel, Asymmetric Property Variation, and Asymmetric Heating
,”
J. Porous Media
,
4
, pp.
137
148
.
14.
Nield
,
D. A.
, and
Kuznetsov
,
A. V.
, 2001, “
The Interaction of Thermal Nonequilibrium and Heterogeneous Conductivity Effects in Forced Convection in Layered Porous Channels
,”
Int. J. Heat Mass Transfer
,
44
, pp.
4369
4373
.
15.
Nield
,
D. A.
, and
Kuznetsov
,
A. V.
, 2007, “
The Effects of Combined Horizontal and Vertical Heterogeneity on the Onset of Convection in a Porous Medium
,”
Int. J. Heat Mass Transfer
,
50
, pp.
2361
2367
, Erratum, 50, pp. 4512–4512.
16.
Nield
,
D. A.
, and
Simmons
,
C. T.
, 2007, “
A Discussion on the Effect of Heterogeneity on the Onset of Convection in a Porous Medium
,”
Transp. Porous Media
,
68
, pp.
413
421
.
17.
Nield
,
D. A.
,
Kuznetsov
,
A. V.
, and
Simmons
,
C. T.
, 2009, “
The Effect of Strong Heterogeneity on the Onset of Convection in a Porous Medium: non–periodic Global Variation
,”
Transp. Porous Media
,
77
, pp.
169
186
.
18.
Nield
,
D. A.
, and
Kuznetsov
,
A. V.
, 2011, “
The Onset of Convection in a Heterogeneous Porous Medium with Vertical Throughflow
,”
Transp. Porous Media
,
88
, pp.
347
355
.
19.
Barletta
,
A.
,
Celli
,
M.
, and
Kuznetsov
,
A. V.
, 2011, “
Transverse Heterogeneity Effects in the Dissipation–Induced Instability of a Horizontal Porous Layer
,”
Trans. ASME J. Heat Transfer
(in press).
20.
Weber
,
J. E.
, 1974, “
Convection in a Porous Medium With Horizontal and Vertical Temperature Gradients
,”
Int. J. Heat Mass Transfer
,
17
, pp.
241
248
.
21.
Barletta
,
A.
, and
Nield
,
D. A.
, 2010, “
Instability of Hadley–Prats Flow With Viscous Heating in a Horizontal Porous Layer
,”
Transp. Porous Media
,
84
, pp.
241
256
.
22.
Barletta
,
A.
,
Celli
,
M.
, and
Nield
,
D. A.
, 2010, “
Unstably Stratified Darcy Flow With Impressed Horizontal Temperature Gradient, Viscous Dissipation and Asymmetric Thermal Boundary Conditions
,”
Int. J. Heat Mass Transfer
,
53
, pp.
1621
1627
.
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