Rarefaction Effect on Friction Factor of Gas Flow in Microchannels

Microfluidic devices are used today in many engineering applications. However, despite much progress in this field, the fundamental understanding of fluid flow and heat transfer on the microscale is still not satisfactory. In this study, the rarefaction effects on the pressure drop for an incompressible flow through silicon microchannels having a rectangular, trapezoidal or double-trapezoidal cross-section are investigated. The roles of the Knudsen number and the cross-section aspect ratio in the friction factor reduction due to the rarefaction are pointed out