Laminar fully developed flow and heat transfer of Robertson–Stiff fluids in a rectangular duct

Abstract

The laminar fully developed flow and heat transfer through a rectangular duct of a viscous incompressible Robertson–Stiff fluid is investigated. Robertson–Stiff fluids are time independent non-Newtonian materials possessing a yield value. The governing momentum and energy equations are solved numerically using finite-difference approximations. We consider two cases of thermal boundary conditions: H1 the "circumferentially constant wall temperature and axially constant wall heat flux" and H2 the "circumferentially and axially constant wall heat flux". The velocity, temperature, the average friction factor and Nusselt numbers for the two cases are computed for various values of the physical parameters. The present results have been compared with the known solutions for Newtonian and power-law fluids and are found to be in good agreement.PACS Nos.: 47.50.+d, 47.15.–x