Abstract




 
   

Vol. 18, No. 4 (November 2005) 331-350   

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  UNSTEADY FREE CONVECTION FROM A SPHERE IN A POROUS MEDIUM WITH VARIABLE SURFACE TEMPERATURE
 
A. Baradaran Rahimi, Taleb Jalali

Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran. 
rahimiab@yahoo.com

 
( Received: December 31, 2004 )
 
 

Abstract    In this paper a transient free convection flow around a sphere with variable surface temperature and embedded in a porous medium has been considered. The temperature of the sphere is suddenly raised and subsequently maintained at values that varies with position on surface. The method of asymptotic expansions is applied for small Rayleigh numbers and then a finite-difference scheme is used to solve the problem numerically for finite values of Rayleigh numbers. Transient and steady-state flow and temperature patterns around the sphere are discussed in details and a comparison between numerical and analytical results has been presented.

 

Keywords    Transient, Rayleigh, Free convection, Sphere, Porous medium, Local Nusselt number

 

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