Numerical simulations have been conducted to study natural convection heat transfer from solid or hollow cylinders in the laminar range of Ra spanning from 104 to 108 for L/D in the range of 0.05(L/D)20. Interesting flow structures around the thin hollow cylinder have been observed for small and large L/D. It has been found that the average Nu for solid or hollow horizontal cylinders in air is marginally higher than when they are on ground for the entire range of L/D and Ra limited up to 107. Up to a Ra of 107 Nu for a solid cylinder in air is higher than that of Nu for a hollow cylinder in air but when Ra exceeds 107 Nu for a hollow cylinder is marginally higher than that of the solid cylinder until an L/D of 0.2. When, L/D rises beyond 0.2 the situation reveres causing Nu for a solid cylinder to be again higher than that of the hollow cylinder when suspended in air. A solid cylinder on ground has higher Nu compared to that of a hollow cylinder on ground up to a Ra of 106. However, for higher Ra of 108 a hollow cylinder on ground has higher Nu compared to that of a solid cylinder on ground until an L/D of 5 and after that the situation reverses again.

References

References
1.
Ayrton
,
W.
, and
Kilgour
,
H.
,
1892
, “
The Thermal Emissivity of Thin Wires in Air
,”
Philos. Trans. R. Soc. A
,
183
(
0
), pp.
371
405
.
2.
Petavel
,
J.
,
1898
, “
On the Heat Dissipated by a Platinum Surface at High Temperatures
,”
Philos Trans. R. Soc. A
,
191
(
0
), pp.
501
524
.
3.
Kennelly
,
A.
,
Wright
,
C.
, and
Bylevelt
,
J. V.
,
1909
, “
The Convection of Heat From Small Copper Wires
,”
Trans. Am. Inst. Electr. Eng.
,
28
(
1
), pp.
363
393
.
4.
Langmuir
,
I.
,
1912
, “
The Convection and Conduction of Heat in Gases
,”
Trans. Am. Inst. Electr. Eng.
,
34
(
6
), pp.
1229
1240
.
5.
Davis
,
A.
,
1922
, “
Natural Convective Cooling in Fluids
,”
Philos. Mag.
,
44
(
263
), pp.
920
940
.
6.
Nelson
,
R.
,
1924
, “
Free Convection Heat in Liquids
,”
Phys. Rev.
,
23
(
1
), pp.
94
103
.
7.
Nusselt
,
W.
,
1929
, “
Heat Dissipation From Horizontal Tubes and Wires to Gases and Liquids
,”
Ver DeutIng
,
73
, pp.
1475
1478
.
8.
Lander
,
C.
,
1942
, “
A Review of Recent Progress in Heat Transfer
,”
J. Inst. Mech. Eng.
,
148
(
1942
), pp.
81
112
.
9.
Tsubouchi
,
T.
, and
Masuda
,
H.
,
1966–1967
, “
Natural Convection Heat Transfer From a Horizontal Circular Cylinder With Small Rectangular Grooves
,”
Sci. Rep. Res. Inst. Tohaku Univ. Ser. B
,
18
, pp.
211
242
.
10.
Penney
,
W. R.
, and
Jefferson
,
T. B.
,
1966
, “
Heat Transfer From an Oscillating Horizontal Wire to Water and Ethylene Glycol
,”
ASME J. Heat Trans.
,
88
(
4
), pp.
359
366
.
11.
Saville
,
D.
, and
Churchill
,
S.
,
1967
, “
Laminar Free Convection in Boundary Layers Near Horizontal Cylinders and Vertical Axisymmetric Bodies
,”
J. Fluid Mech.
,
29
(
2
), pp.
391
399
.
12.
Churchill
,
S.
, and
Chu
,
H.
,
1975
, “
Correlating Equations for Laminar and Turbulent Free Convection From a Horizontal Cylinder
,”
Int. J. Heat Mass Trans.
,
18
(
9
), pp.
1049
1053
.
13.
Nakai
,
S.
, and
Okazaki
,
T.
,
1975
, “
Heat Transfer Form a Horizontal Circular Wire at Small Reynolds and Grashof Numbers-I
,”
Int. J. Heat Mass Trans.
,
18
, pp.
387
396
.
14.
Merkin
,
J.
,
1977
, “
Free Convection Boundary Layers on Cylinders of Elliptic Cross Section
,”
ASME J. Heat Trans.
,
99
(
3
), pp.
453
457
.
15.
Kuehn
,
T.
, and
Goldstein
,
R.
,
1980
, “
Numerical Solution to the Navier–Stokes Equations for Laminar Natural Convection About a Horizontal Isothermal Circular Cylinder
,”
Int. J. Heat Mass Trans.
,
23
(
7
), pp.
971
979
.
16.
Farouk
,
B.
, and
Güçeri
,
S. I.
,
1981
, “
Natural Convection From a Horizontal Cylinder-Laminar Regime
,”
ASME J. Heat. Trans.
,
103
(
3
), pp.
522
527
.
17.
De Socio
,
L.
,
1983
, “
Laminar Free Convection Around Horizontal Circular Cylinders
,”
Int. J. Heat Mass Trans.
,
26
(
11
), pp.
1669
1677
.
18.
Al-Arabi
,
M.
, and
Khamis
,
M.
,
1982
, “
Natural Convection Heat Transfer From Inclined Cylinders
,”
Int. J. Heat Mass Trans.
,
25
(
1
), pp.
3
15
.
19.
Wang
,
P.
,
Khawita
,
R.
, and
Nguyen
,
D. L.
,
1990
, “
Transient Laminar Natural Convection From Horizontal Cylinders
,”
Int. J. Heat Mass Transfer
,
34
(
6
), pp.
1429
1442
.
20.
Saitoh
,
T.
,
Sajiki
,
T.
, and
Maruhara
,
K.
,
1993
, “
Bench Mark Solutions to Natural Convection Heat Transfer Problem Around a Horizontal Circular Cylinder
,”
Int. J. Heat Mass Trans.
,
36
(
5
), pp.
1251
1259
.
21.
Chouikh
,
T.
,
Guizani
,
A.
, and
Maalej
,
M.
,
1997
, “
Numerical Study of Laminar Natural Convection Flow Around Horizontal Isothermal Cylinder
,”
Renewable Energy
,
13
(
1
), pp.
71
78
.
22.
Molla
,
M. M.
,
Paul
,
S. C.
, and
Hossain
,
A.
,
2008
, “
Natural Convection Flow for a Horizontal Cylinder With Uniform Heat Flux in Presence of Heat Generation
,”
Appl. Math. Model.
,
33
, pp.
3226
3236
.
23.
Molla
,
M. M.
,
Hossain
,
M. A.
, and
Gorla
,
R. S. R.
,
2005
, “
Natural Convection Flow From Isothermal Horizontal Circular Cylinder With Temperature Dependent Viscosity
,”
Heat Mass Transfer
,
41
(
7
), pp.
594
598
.
24.
Atayilmaz
,
S. O.
, and
Teke
,
I.
,
2009
, “
Experimental and Numerical Study of the Natural Convection From a Heated Horizontal Cylinder
,”
Int. Commun. Heat Mass Trans.
,
36
(
7
), pp.
731
738
.
25.
Ashjaee
,
M.
,
Yazdani
,
S.
,
Bigham
,
S.
, and
Yousefi
,
T.
,
2011
, “
Experimental and Numerical Investigation on Free Convection From Horizontal Cylinder Located Above an Adiabatic Surface
,”
Heat Transfer Eng.
,
33
(
3
), pp.
213
214
.
26.
Mehrizi
,
A. A.
,
Farhadi
,
M.
,
Afrouzi
,
H. H.
,
Shayamehr
,
S.
, and
Lotfizadeh
,
H.
,
2013
, “
Lattice Boltzmann Simulation of Natural Convection Flow Around a Horizontal Cylinder Located Beneath an Insulated Plate
,”
J. Theor. Appl. Phys.
,
51
(
3
), pp.
729
739
.
27.
Kuehner
,
J. P.
,
Hamed
,
A. M.
, and
Mitchell
,
J. D.
,
2015
, “
Experimental Investigation of Free Convection Velocity Boundary Layer and Plume Formation Region for a Heated Horizontal Cylinder
,”
Int. J. Heat Mass Transfer
,
82
, pp.
78
97
.
28.
Sedaghat
,
M. H.
,
Yaghoubi
,
M.
, and
Mafhrebi
,
M. J.
,
2015
, “
Analysis of Natural Convection Heat Transfer From a Cylinder Enclosed in a Corner of Two Adiabatic Wall
,”
Exp. Therm. Fluid Sci.
,
62
, pp.
78
97
.
29.
Tsung-Yen
,
N.
,
1993
, “
Effect of Wall Condition on Natural Convection Over a Vertical Slender Hollow Circular Cylinder
,”
Appl. Sci. Res.
,
54
, pp.
39
50
.
30.
Chang
,
L. C.
,
2008
, “
Numerical Simulation of Natural Convection of Micro Polar Fluid Flow Along Slender Hollow Cylinder With Wall Conduction Effect
,”
Non Linear Sci. Numer. Simul.
,
13
, pp.
9
20
.
31.
Mamun
,
M. M. H.
,
Rahman
,
M. M.
,
Billah
,
M. M.
, and
Saidur
,
R.
,
2010
, “
A Numerical Study on the Effect of a Hollow Cylinder on Mixed Convection in a Ventilated Cavity
,”
Int. Commun. Heat Mass Transfer
,
37
(
9
), pp.
1326
1334
.
32.
Billah
,
M. M.
,
Rahman
,
M. M.
,
Sharif
,
M. U.
,
Rahim
,
N. A.
,
Saidur
,
R.
, and
Hassanuzzaman
,
M.
,
2011
, “
Numerical Analysis of Fluid Flow Due to Mixed Convection in a Lid-Driven Cavity Having a Heated Circular Hollow Cylinder
,”
Int. Commun. Heat Mass Transfer
,
38
(
8
), pp.
1093
1103
.
33.
Rani
,
H. P.
, and
Reddy
,
G. J.
,
2011
, “
Conjugate Transient Free Convective Heat Transfer From a Vertical Slender Hollow Cylinder With Heat Generation Effect
,”
Appl. Math.
,
1
(
2
), pp.
90
98
.
34.
Ansys,
2013
, “
Ansys Fluent, Release 15.0, User Manual
,”
ANSYS, Inc.
,
Canonsburg, PA
.
35.
Senapati
,
J. R.
,
Dash
,
S. K.
, and
Roy
,
S.
,
2016
, “
Numerical Investigation of Natural Convection Heat Transfer Over Annular Finned Horizontal Cylinder
,”
Int. J. Heat Mass Transfer
,
96
, pp.
330
345
.
36.
Senapati
,
J. R.
,
Dash
,
S. K.
, and
Roy
,
S.
,
2016
, “
3D Numerical Study of the Effect of Eccentricity on Heat Transfer Characteristics Over Horizontal Cylinder Fitted With Annular Fins
,”
Int. J. Therm. Sci.
,
108
, pp.
28
39
.
37.
Morgan
,
V. T.
,
1975
,
The Overall Convective Heat Transfer From Smooth Circular Cylinders
, Academic Press, New York.
You do not currently have access to this content.