LAMINAR-FLOW HEAT-TRANSFER IN THE ENTRANCE REGION OF CONCENTRIC ANNULI FOR POWER LAW FLUIDS

Abstract

Finite element analysis for the laminar flow heat transfer in the entrance region of concentric annuli has been carried out for power law fluids. Simultaneously developing hydrodynamic and thermal boundary layers have been considered with one wall of the annulus isothermal and the other adiabatic. A linearization iterative procedure has been used to solve the hydrodynamic entry length problem. The results are used for the solution of the energy equation. Numerical calculations 'have been carried out for various values of the Prandtl number, aspect ratio and the flow behaviour index. The local Nusselt number and mixing cup temperature have been calculated. The comparison of particular results for a Newtonian fluid with those obtained earlier using a finite difference technique indicates that the present analysis gives more symmetrical results and closer to the experimental values.