INFLUENCE OF VISCOSITY VARIATION ON SURFACE DRIVEN CONVECTION IN A COMPOSITE LAYER WITH A BOUNDARY SLAB OF FINITE THICKNESS AND FINITE THERMAL CONDUCTIVITY

2020 ◽  
Vol 19 (2) ◽  
pp. 269-288
Author(s):  
Y. H. Gangadharaiah ◽  
K. Ananda
Keyword(s):  
Thermal Conductivity ◽  
Finite Thickness ◽  
Composite Layer ◽  
Viscosity Variation

Thermal Stability of Two Fluid Layers Separated by a Solid Interlayer of Finite Thickness and Thermal Conductivity

1984 ◽  
Vol 106 (3) ◽  
pp. 605-612 ◽  
Author(s):  
I. Catton ◽  
J. H. Lienhard
Keyword(s):  
Thermal Conductivity ◽  
Fluid Layer ◽  
Heated Surface ◽  
Finite Thickness ◽  
Fluid Layers ◽  
The Stability ◽  
Stability Limits ◽  
Range Of Values ◽  
Two Fluid ◽  
Thermal Stability Of

Stability limits of two horizontal fluid layers separated by an interlayer of finite thermal conductivity are determined. The upper cooled surface and the lower heated surface are taken to be perfectly conducting. The stability limits are found to depend on the ratio of fluid layer thicknesses, the ratio of interlayer thickness to total fluid layer thickness, and the ratio of fluid thermal conductivity to interlayer thermal conductivity. Results are given for a range of values of each of the governing parameters.

scholarly journals MHD free convection flow along a vertical flat plate with thermal conductivity and viscosity depending on temperature

2010 ◽  
Vol 6 (2) ◽  
pp. 72-83 ◽  
Author(s):  
Rehena Nasrin ◽  
Md. Abdul Alim
Keyword(s):  
Thermal Conductivity ◽  
Boundary Layer ◽  
Free Convection ◽  
Joule Heating ◽  
Convection Flow ◽  
Temperature Profiles ◽  
Free Convection Flow ◽  
Variation Parameter ◽  
Viscosity Variation ◽  
Vertical Flat Plate

In this present work the effects of temperature dependent viscosity and thermal conductivity on the coupling of conduction and Joule heating with MHD free convection flow along a semi-infinite vertical flat plate have been analyzed. The governing boundary layer equations with associated boundary conditions for this phenomenon are transformed to non-dimensional form using the appropriate variables. By the help of the implicit finite difference method with Keller–box scheme, the resulting non-linear system of partial differential equation is then solved numerically. The purpose of this paper is to study the skin friction coefficient, the surface temperature, the velocity and the temperature profiles over the whole boundary layer for different values of the Prandtl number Pr, the magnetic parameter M, the thermal conductivity variation parameter, the viscosity variation parameter and the Joule heating parameter J. The results indicate that the flow pattern, temperature field and rate of heat transfer are significantly dependent on the above mentioned parameters. The local skin friction co-efficient and the surface temperature profiles for different values of viscosity variation parameter are compared with previously published works and are found to be in good agreement.Keywords: Viscosity; thermal conductivity; Joule heating; MHD; conduction; free convection.DOI: 10.3329/jname.v6i2.4994

Thermal Conductivity of Ceramic Nanocomposites – The Phase Mixture Modeling Approach

2010 ◽  
Vol 71 ◽  
pp. 68-73 ◽  
Author(s):  
Willi Pabst ◽  
Jan Hostaša
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundary ◽  
Nanocrystalline Materials ◽  
Effective Properties ◽  
Finite Thickness ◽  
Mixture Modeling ◽  
Boundary Phase ◽  
Modeling Approach ◽  
Phase Mixture ◽  
Mixture Modeling Approach

In nanocrystalline materials the grain boundaries must be considered as regions of finite thickness with properties different from the crystalline bulk material present in the crystallite cores. Thus, dense (i.e. pore-free) single-phase nanocrystalline materials can be considered as quasi-twophase systems whose effective properties can be calculated when quantitative thickness information is available and the property value of the grain boundary phase can be reliably estimated. Similarly, dense two-phase nanocomposites may be considered as quasi-three-phase systems and their effective properties can be predicted using an analogous phase mixture modeling approach. In this contribution this is done for the thermal conductivity of alumina-zirconia nanocomposites. A twostage homogenization procedure is applied, consisting of a first step in which the alumina-zirconia composite is treated as a symmetric-cell material, and a second step in which the highly disordered grain boundary phase is treated as a matrix-phase, coating the crystallite cores. The individual averaging steps are discussed with respect to the two- and three-point bounds, and the resulting grain size dependence is compared with that of pure alumina and zirconia, and literature data.

Natural Convection Heat Transfer in a Vertical Air Layer Partitioned Into Cubical Enclosures of Finite Wall Thermal Conductivity and Thickness

1999 ◽  
Author(s):  
Y. Yamaguchi ◽  
Y. Asako
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Natural Convection ◽  
Wall Thickness ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Wide Range

Abstract Three-dimensional natural convection heat transfer characteristics in a vertical air layer partitioned into cubical enclosures of finite wall thermal conductivity and finite thickness were obtained numerically. The outer surfaces of the enclosure are prescribed at different temperatures. These walls are often encountered in applications such as door panels and thermal insulation boards. The analyses were performed for finite wall thickness and conductivity, for Ra = 104 and 105 and for a wide range of wall thickness and thermal. The results were presented in form of temperature distributions and contour plots of Num and Qwall/Qtotal. From comparison of the results with ideal boundary conditions, a correlation for heat transfer for partitioned walls was developed. It was shown from the results that the ratio of heat transfer into the partition walls to the total heat transfer from the hot wall is a function of the product of wall thermal conductivity and thickness.

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