Gas Flow Through Smooth And Rough Microchannels
In this paper we present experimental measurements of friction factor for gas flow through rectangular crosssection microchannels. (100) and (110) silicon wafers were used to fabricate microchannels with smooth and
rough surfaces, respectively. The instrumentation includes local pressure measurement along the microchannel
length to determine the axial pressure profile. Sensors to directly measure the microchannel surface temperature are currently under development to enable calculation of the local convection heat transfer coefficient. The microchannels are etched into silicon wafers, capped with smooth glass, and have hydraulic diameters between 4 and 100-microns. All measurements were made in the laminar flow regime with Reynolds numbers ranging from 0.1 to 1000. The objective of the investigation is to (1) verify the continuum based predictions of friction factor for large microchannels; (2) determine if the friction factor is dependent on the surface roughness for microscale flows; and (3) identify the Knudsen number (ratio of mean free path to
channel depth) at which the friction factor begins to deviate from continuum behavior.