Thermal Instability of Natural Convection Flow over a Horizontal Ice Cylinder Encompassing a Maximum Density Point

1980 ◽  
Vol 102 (2) ◽  
pp. 261-267 ◽  
Author(s):  
T. Saitoh ◽  
K. Hirose
Keyword(s):  
Perturbation Method ◽  
Thermal Instability ◽  
Three Dimensional ◽  
Wave Number ◽  
Convection Flow ◽  
Governing Equations ◽  
Natural Convection Flow ◽  
Melting Front ◽  
Transfer Region ◽  
Minimum Heat

The problem of three-dimensional thermal instability over a horizontal ice cylinder which occurs in a minimum heat transfer region has been solved. A fully numerical method was applied to the governing equations in the transverse and longitudinal planes, which were simplified to two-dimensional. The perturbation method was employed to obtain the wave number. The appearance of a convexo-concave melting front, which was predicted by a previous experiment, was clearly explained by the convection pattern along the cylinder. The transient process of onset of stable vortices around a cylinder was clarified by streamlines and isotherms. Comparing the wave numbers obtained by the numerical and the small perturbation methods, it is concluded that the perturbation method cannot be effectively applied to problems involving density inversion.

scholarly journals The response of skin friction, wall heat transfer and pressure drop to wall waviness in the presence of buoyancy

1982 ◽  
Vol 5 (3) ◽  
pp. 585-594 ◽  
Author(s):  
C. N. B. Rao ◽  
K. S. Sastri
Keyword(s):  
Heat Transfer ◽  
Viscous Incompressible Fluid ◽  
Temperature Fields ◽  
Wave Number ◽  
Convection Flow ◽  
Governing Equations ◽  
Natural Convection Flow ◽  
Flow And Heat Transfer ◽  
Fluid Properties ◽  
Laminar Natural Convection

Laminar natural convection flow and heat transfer of a viscous incompressible fluid confined between two long vertical wavy walls has been analysed taking the fluid properties constant and variable. In particular, attention is restricted to estimate the effects of viscous dissipation and wall waviness on the flow and heat transfer characteristics. Use has been made of a linearization technique to simplify the governing equations and of Galerkin's method in the solution. The solutions obtained for the velocity and the temperature-fields hold good for all values of the Grashof number and wave number of the wavy walls.

scholarly journals The Effects Of Radiation And Heat Generation On Magnetohydrodynamic(MHD) Natural Convection Flow Along A Vertical Flat Plate In Presence Of Viscous Dissipation

1970 ◽  
Vol 6 (1) ◽  
pp. 20-29
Author(s):  
Mohammad Mokaddes Ali ◽  
Rowsanara Akhter ◽  
NHM A Azim ◽  
MA Maleque
Keyword(s):  
Flat Plate ◽  
Viscous Dissipation ◽  
Heat Generation ◽  
Convection Flow ◽  
Governing Equations ◽  
Natural Convection Flow ◽  
Dissipation Parameter ◽  
Effects Of Radiation ◽  
Generation Parameter ◽  
Vertical Flat Plate

This article investigates the effects of radiation and heat generation on magnetohydrodynamic( MHD) natural convection flow of an incompressible viscous electrically conducting fluid along a vertically placed flat plate in presence of viscous dissipation and heat conduction. Appropriate transformations were employed to transform governing equations of this flow into dimensionless form and then solved using the implicit finite difference method with Keller box scheme. The resulting numerical solutions of transformed governing equations are presented graphically in terms of velocity profile, temperature distribution, skin friction coefficient and surface temperature and the effects of magnetic parameter (M), radiation parameter (R), Prandtl number (Pr) and heat generation parameter (Q) and viscous dissipation parameter (N) on the flow have been studied with the help of graphs. Keywords: Radiation; Heat Generation Parameter; Viscous Dissipation Parameter; MHD; Finite Difference Method; Vertical Flat Plate. DOI: http://dx.doi.org/10.3329/diujst.v6i1.9330 DIUJST 2011; 6(1): 20-29

Numerical Solutions of Natural Convection Flow of a Dusty Nanofluid About a Vertical Wavy Truncated Cone

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Sadia Siddiqa ◽  
Naheed Begum ◽  
M. A. Hossain ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Natural Convection ◽  
Mass Transport ◽  
Numerical Solutions ◽  
Convection Flow ◽  
Governing Equations ◽  
Natural Convection Flow ◽  
Two Phase ◽  
Heat And Mass Transport ◽  
Implicit Finite Difference ◽  
Control Skin

This paper reports the numerical results for the natural convection flow of a two-phase dusty nanofluid along a vertical wavy frustum of a cone. The general governing equations are transformed into parabolic partial differential equations, which are then solved numerically with the help of implicit finite difference method. Comprehensive flow formations of carrier and dusty phases are given with the aim to predict the behavior of heat and mass transport across the heated wavy frustum of a cone. The effectiveness of utilizing the nanofluids to control skin friction and heat and mass transport is analyzed. The results clearly show that the shape of the waviness changes when nanofluid is considered. It is shown that the modified diffusivity ratio parameter, NA, extensively promotes rate of mass transfer near the vicinity of the cone, whereas heat transfer rate reduces.

Numerical Simulations of an Unsteady Confined Natural Convection Flow

2009 ◽  
Author(s):  
Gillian Leplat ◽  
Emmanuel Laroche ◽  
Philippe Reulet ◽  
Pierre Millan
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Large Scale ◽  
Critical Rayleigh Number ◽  
Three Dimensional ◽  
High Amplitude ◽  
Joint Fluid ◽  
Convection Flow ◽  
Two Dimensional ◽  
Natural Convection Flow

A two-dimensional numerical analysis of a laminar natural convection flow within an air-filled enclosure is proposed in this paper from an unstable configuration previously studied experimentally. The flow is driven by a heated square-section cylinder located at the center of a square-section enclosure. Instabilities are observed for an aspect ratio (height of the cylinder over the height of the cavity) of 0.4 and cause the flow to turn into a three-dimensional and unsteady regime characterized by a symmetry breaking and large scale high amplitude flappings around the cylinder. The multi-physic computational software CEDRE, developed at the ONERA, is used to study this unstable behavior and a time-dependent compressible flow solver is used to perform the two-dimensional simulations under the low Mach number approximation, corresponding to the mid-depth cross-section of the enclosure from the experimental configuration. The first results on the investigation of the first unstable modes confirm the onset of the instabilities at the Rayleigh number of the experiment with asymmetrical motions of the fluid around the cylinder. Further analyses highlight the critical Rayleigh number that defines the instability threshold of the first bifurcation which origin and nature could have been identified. Finally, joint fluid-solid simulations are performed to determine more precisely the role of boundary conditions in the onset of instabilities.

scholarly journals Asymmetric natural convection flow in three dimensional attic space

2019 ◽  
Author(s):  
Cui Huimin ◽  
Xu Feng ◽  
C. Saha Suvash ◽  
Liu Qingkuan
Keyword(s):  
Natural Convection ◽  
Three Dimensional ◽  
Convection Flow ◽  
Natural Convection Flow
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