Thermal boundary layer in liquid metals with variable thermal conductivity

1978 ◽  
Vol 34 (2-3) ◽  
pp. 179-187 ◽  
Author(s):  
M. Arunachalam ◽  
N. R. Rajappa
Keyword(s):  
Thermal Conductivity ◽  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Liquid Metals ◽  
Variable Thermal Conductivity

scholarly journals ON CORRECTION TO TEMPERATURE FIELD DUE TO VARIABLE THERMAL CONDUCTIVITY IN CASE OF BOUNDARY LAYER FLOW PAST A MOVING CYLINDER WITH SUCTION

2014 ◽  
Vol 44 (4) ◽  
pp. 351-354
Author(s):  
R. R. RANGI ◽  
N. AHMAD
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Viscous Incompressible Fluid ◽  
Liquid Metals ◽  
Variable Thermal Conductivity ◽  
Moving Cylinder ◽  
Layer Flow ◽  
Study Heat Transfer

The boundary layer flow of viscous incompressible fluid over a moving cylinder with suction has been considered to study heat transfer with variable thermal conductivity. The heat transfer is affected by thermal conductivity for the liquid metals within 0ºF to 400ºF range. In this case, we observe that the transfer of heat behaves differently in two different regions: 0  1 and  >1. Hence, we solve the two boundary value problems to draw out recommendations. The results have been discussed graphically.

scholarly journals Influence of Variable Thermal Conductivity on MHD Boundary Layer Slip Flow of Ethylene-Glycol Based Cu Nanofluids over a Stretching Sheet with Convective Boundary Condition

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
N. Bhaskar Reddy ◽  
T. Poornima ◽  
P. Sreenivasulu
Keyword(s):  
Thermal Conductivity ◽  
Boundary Layer ◽  
Boundary Condition ◽  
Stretching Sheet ◽  
Volume Fraction ◽  
Slip Flow ◽  
Velocity Slip ◽  
Convective Boundary Condition ◽  
Variable Thermal Conductivity ◽  
Convective Boundary

An analysis is carried out to investigate the influence of variable thermal conductivity and partial velocity slip on hydromagnetic two-dimensional boundary layer flow of a nanofluid with Cu nanoparticles over a stretching sheet with convective boundary condition. Using similarity transformation, the governing boundary layer equations along with the appropriate boundary conditions are transformed to a set of ordinary differential equations. Employing Runge-kutta fourth-order method along with shooting technique, the resultant system of equations is solved. The influence of various pertinent parameters such as nanofluid volume fraction parameter, the magnetic parameter, radiation parameter, thermal conductivity parameter, velocity slip parameter, Biot number, and suction or injection parameter on the velocity of the flow field and heat transfer characteristics is computed numerically and illustrated graphically. The present results are compared with the existing results for the case of regular fluid and found an excellent agreement.

scholarly journals Controlling thermal chaos in the mantle by positive feedback from radiative thermal conductivity

2002 ◽  
Vol 9 (3/4) ◽  
pp. 311-323 ◽  
Author(s):  
F. Dubuffet ◽  
D. A. Yuen ◽  
E. S. G. Rainey
Keyword(s):  
Thermal Conductivity ◽  
Boundary Layer ◽  
Mantle Convection ◽  
Variable Thermal Conductivity ◽  
Time Dependent ◽  
Internal Heating ◽  
Chaotic Flows ◽  
Deep Mantle ◽  
Radiative Conductivity ◽  
Radiative Thermal Conductivity

Abstract. The thermal conductivity of mantle materials has two components, the lattice component klat from phonons and the radiative component krad due to photons. These two contributions of variable thermal conductivity have a nonlinear dependence in the temperature, thus endowing the temperature equation in mantle convection with a strongly nonlinear character. The temperature derivatives of these two mechanisms have different signs, with ∂klat /∂T negative and dkrad /dT positive. This offers the possibility for the radiative conductivity to control the chaotic boundary layer instabilities developed in the deep mantle. We have parameterized the weight factor between krad and klat with a dimensionless parameter f , where f = 1 corresponds to the reference conductivity model. We have carried out two-dimensional, time-dependent calculations for variable thermal conductivity but constant viscosity in an aspect-ratio 6 box for surface Rayleigh numbers between 106 and 5 × 106. The averaged Péclet < Pe > numbers of these flows lie between 200 and 2000. Along the boundary in f separating the chaotic and steady-state solutions, the < Pe > number decreases and the Nusselt number increases with internal heating, illustrating the feedback between internal heating and radiative thermal conductivity. For purely basal heating situation, the time-dependent chaotic flows become stabilized for values of f of between 1.5 and 2. The bottom thermal boundary layer thickens and the surface heat flow increases with larger amounts of radiative conductivity. For magnitudes of internal heating characteristic of a chondritic mantle, much larger values of f , exceeding 10, are required to quench the bottom boundary layer instabilities. By isolating the individual conductive mechanisms, we have ascertained that the lattice conductivity is partly responsible for inducing boundary layer instabilities, while the radiative conductivity and purely depth-dependent conductivity exert a stabilizing influence and help to control thermal chaos developed in the deep mantle. These results have been verified to exist also in three-dimensional geometry and would argue for the need to consider the potentially important role played by radiative thermal conductivity in controlling chaotic flows in time-dependent mantle convection, the mantle heat transfer, the number of hotspots and the attendant mixing of geochemical anomalies.

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