Effects of viscous dissipation on slip-flow heat transfer in a micro annulus

This study deals numerically with the laminar slip-flow forced convection in a micro annulus with constant wall temperature. The solution takes the effects of viscous dissipation, velocity-slip and temperature-jump conditions at the surface into considerations. A hybrid application of the Laplace transformation technique and the local adaptive differential quadrature method (La-DQM) is used to solve the energy equation for the developing temperature field. Of interest are the effects of the Brinkman number Br, the Knudsen number Kn, and the radius ratio beta of inner to outer cylinders on the temperature distribution and the Nusselt number. The results indicate that fully developed Nusselt number increases with an increase in the radius ratio beta or a decrease in the Knudsen number Kn, but it is rather insensitive to the Brinkman number. The local Nusselt number in the thermal entrance region increases as Br increases. Comparisons are also made of the dimensionless temperature gradient at the outer cylinder between the present results and published data for the circular tube case beta = 0, and the agreement is found out to be generally good. (C) 2009 Elsevier Ltd. All rights reserved.