The overall object of this paper is a systematic study of gaseous flows and thermal transport in two-dimensional micro- and nano-channels using direct simulation Monte Carlo (DSMC) method. The flows are often encountered in MEMS, NEMS in diverse fields like space propulsion, particle physics. The effects of compressibility and rarefaction on the flows were investigated through simulating flows (a) with same outlet Knudsen number (Kn) but different pressure drop ratios and (b) with low-pressure drop ratio but different Kn numbers, respectively. For the situation (a), it was found that the high pressure drop flow (pressure ratio: 4.5) show a 15% higher friction coefficient than that of a fully developed flow while the low pressure drop flow (pressure ratio: 1.5) is consistent with incompressible flow prediction. However, for the situation (b), the rarefactions actually reduce the friction coefficients by 22% (Kn: 0.083) and 36% (Kn: 0.043) and an apparent velocity slips along the channel wall exist for both flows. The DSMC results show high magnitude and densely distributed surface roughness induce higher friction coefficient. In the thermal transport study, both temperature distribution and the effects of rarefaction and surface roughness on Nusselt number (Nu) are discussed by comparing with those of fully developed flows.
Journal: TechConnect Briefs
Volume: 3, Nanotechnology 2008: Microsystems, Photonics, Sensors, Fluidics, Modeling, and Simulation – Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, Volume 3
Published: June 1, 2008
Pages: 363 - 366
Industry sectors: Medical & Biotech | Sensors, MEMS, Electronics
Topic: Micro & Bio Fluidics, Lab-on-Chip