International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2557

Full Length Research Paper

Analysis of entropy generation in a variable viscosity fluid flow between two concentric pipes with a convective cooling at the surface

M. S. Tshehla1* and O. D. Makinde2      
1Department of Mathematics, Faculty of Military Science, University of Stellenbosch, P/Bag X2, Saldanha, 7395, South Africa. 2Institute for Advance Research in Mathematical Modelling and Computations, Cape Peninsula University of Technology, P. O. Box 1906, Bellville 7535, South Africa.  
Email: [email protected]

  •  Accepted: 29 July 2011
  •  Published: 23 October 2011


Entropy generation rate in a variable viscosity liquid flowing steadily through two concentric cylindrical pipes with convective cooling at the pipe surface, are studied using the second law analysis. The outer system is assumed to exchange heat with the ambient following Newton’s cooling law, and the fluid viscosity model varies as an inverse linear function of temperature. The resulting equations and the boundary conditions are solved using the fourth Order Runge-Kutta scheme and an efficient shooting technique. Numerical expressions for fluid velocity and temperature are derived and utilised to obtain expressions for volumetric entropy generation numbers, irreversibility distribution ratio and the Bejan number in the flow field.


Key words: Pipe flow, variable viscosity, entropy generation, convective cooling, irreversibility analysis.