scholarly journals Modelling Turbulent Heat Transfer in a Natural Convection Flow

2014 ◽  
Vol 02 (07) ◽  
pp. 662-670 ◽  
Author(s):  
Claudia Zimmermann ◽  
Rodion Groll
1988 ◽  
Vol 110 (1) ◽  
pp. 116-125 ◽  
Author(s):  
P. A. Litsek ◽  
A. Bejan

The natural convection flow and heat transfer between two enclosures that communicate through a vertical opening is studied by considering the evolution of an enclosed fluid in which the left half is originally at a different temperature than the right half. Numerical experiments show that at sufficiently high Rayleigh numbers the ensuing flow is oscillatory. This and other features are anticipated on the basis of scale analysis. The time scales of the oscillation, the establishment of thermal stratification, and eventual thermal equilibrium are determined and tested numerically. At sufficiently high Rayleigh numbers the heat transfer between the communicating zones is by convection, in accordance with the constant-Stanton-number trend pointed out by Jones and Otis (1986). The range covered by the numerical experiments is 102 < Ra < 107, 0.71 < Pr < 100, and 0.25 < H/L < 1.


2008 ◽  
Author(s):  
Esam M. Alawadhi

Natural convection flow in a cube with a heated strip is solved numerically. The heated strip is attached horizontally to the front wall and maintained at high temperature, while the entire opposite wall is maintained at low temperature. The heated strip simulates an array of electronic chips The Rayleigh numbers of 104, 105, and 106 are considered in the analysis and the heated strip is horizontally attached to the wall. The results indicate that the heat transfer strongly depends on the position of the heated strip. The maximum Nusselt number can be achieved if the heater is placed at the lower half of the vertical wall. Increasing the Rayleigh number significantly promotes heat transfer in the enclosure. Flow streamlines and temperature contours are presented, and the results are validated against published works.


2013 ◽  
Vol 18 (4) ◽  
pp. 1201-1220
Author(s):  
G.S. Seth ◽  
G.K. Mahato ◽  
S. Sarkar

Abstract An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.


Sign in / Sign up

Export Citation Format

Share Document