Investigations of physical effects in microchannels by numerical simulation

• Main Authors: Kuan-Hung Lin, 林冠宏
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/29287417164808488836

碩士 === 國立中央大學 === 機械工程研究所 === 91 === This work studies the compressible gaseous flow in microchannels (diameter size ranging from 0.01 μm to 0.01 m) using the FEMLAB software. Simulations are performed by solving Navier-Stokes equations with modification wall boundary conditions (slip velocity and temperature jump). The flow regime simulated is from the slip flow upto the transitional flow, which consist of the following flow parameters: 0.224≦Kn≦3.44, 10-3≦Re≦800 and 0.5x10-3≦Ma≦0.84. In order to thoroughly analyze various physical effects in the microchannel flow, this work studies multiphysics effects (rarefaction, compressibility, viscous dissipation, reversible work) on the thermal-flow characteristics of the microchannel. Results reveal several interesting features: 1) as the inlet pressure increase, the streamwise nonlinear pressure distribution appears visibly; 2) the slip flow has a higher mass flowrate than that of the nonslip flow; 3) compressibility effect cause the local friction factor increases with increasing local Ma; 4) due to high velocity gradients in the microchannel flow, viscous dissipation and reversible work can not be neglected; 5) first-order slip velocity gives unrealistically over-prediction of velocity at transitional flow regime, and the new continuum based slip model is extended successfully to the transitional flow regime.