Comparison the Effects of Compressibility and Rarefaction for Gas Flow in Microchannels with Different Cross-Section

Microchannels and microtubes are basic elements of microfluidic devices that have wide usage in medicine and industry, so analyses of optimal design of fluid flow in these channels is important. A number of different designs have been done recently about the microchannels, but there isn’t a comprehensive survey on different cross-sections for a particular usage of these channels yet. Therefore in this paper, it has been tried to achieve this goal. Micro heat exchangers are one of devices that use gas flow and micro channels widely. Rarefaction and compressibility are two important effects that should be considered in the gas flow. Knudsen number and Mach number are two non dimensional parameters that show effects of Rarefaction and compressibility. Rectangular, elliptic, circular and trapezoidal, are common channel shapes and have wide practical applications that Rarefaction and compressibility effect have been investigated on them, in this paper. It is obvious that less shear stress on the wall lead to less resistance against fluid’s motion. In the comprehensive survey on different cross-section in the same condition, observed that the elliptical cross-section has lower shear stress. According to this fact that the friction factor decreases by increasing the rarefaction, and comparison made between rectangular and circular cross-section showed that circular channel has lower shear stress.

کلیدواژه ها:

Compressibility ، Microchannel ، Rarefaction ، Friction Factor ، Cross-section