Slip Velocity in Flow and Heat Transfer of Non-newtonian Fluids in Microchannels

Abstract

The steady-state fully-developed laminar flow of non-Newtonian power-law fluids is examined in a circular microchannel with slip boundary condition and under an imposed constant wall heat flux. Effects of slip as well as the hydrodynamic and thermal key parameters on heat transfer and entropy generation are investigated. The results reveal that increasing the Brinkman number and the flow behavior index both lead to increasing the entropy generation and decreasing the Nusselt number. In heating process, the temperature difference between the fluid and the wall decreases as the slip coefficient increases; similar trend may or may not be observed for cooling process, determined by the range of the slip coefficient as well as the Brinkman number. An increase in the slip coefficient leads to an increase in both the Nusselt number and the Bejan number, whereas it gives rise to a decrease in entropy generation. For each particular value of the slip coefficient, the Nusselt number approaches a specific value as the Brinkman number and/or the flow behavior index increases. An increase in the flow behavior index or a decrease in the slip coefficient results in incrementing the average entropy generation.