ENTRANCE REGION FLOWS IN RECTANGULAR MICROCHANNELS WITH CONSTANT WALL TEMPERATURE

摘要

Rarefied gas flow and heat transfer in the entrance region of rectangular microchannels are investigated numerically in the slip flow regime. A control-volume based numerical scheme is used to solve the Navier-Stokes and energy equations with velocity slip and temperature jump conditions at the walls. The effects of variations in Reynolds number (0.1 ≤ Re ≤ 100), channel aspect ratio (0 ≤ α~* ≤ 1) and Knudsen number (0 ≤ Kn ≤ 0.1) are studied on the flow development, slip flow heat transfer, and key parameters like the friction factor and the Nusselt number. For simultaneously developing flow and heat transfer, major reductions in friction coefficients and heat transfer rates are observed in the entrance region due to rarefaction effects, which also extend to the fully developed region, however at much lower levels.