Abstract

Rarefaction and Compressibility Effects on Steady or Transient Gas Flows in Microchannels

Starting from an analysis of the different significant length scales, we show the major part played by rarefaction in gas microflows, and the different flow regimes encountered in microchannels. We summarize the main theoretical and experimental results from the literature about steady pressure-driven or thermally-driven gas microflows. Because it is very frequent in microchannels, the slip flow regime is more detailed and the question of the choice of appropriate boundary conditions is discussed.

The case of pulsed flows is also presented, for this kind of flow is encountered in many micropumps. We show the influence of slip on the frequency behavior (pressure gain and phase) of microchannels. A semi-analytical model for tapered microchannels allows to point out a diode effect, which depends on the frequency. This diode effect may be reversed, when we shrink the dimensions from a few hundred to a few micrometers.

Brief Bio

Stephane Colin is a Professor of mechanical engineering at the National Institute of Applied Sciences (INSA) of Toulouse, France. He obtained an Engineer degree from ENSEEIHT in 1987 and received his Ph.D. in fluid mechanics from the Polytechnic National Institute of Toulouse in 1992. He created in 1999 and currently leads the Microfluidics Group of the Hydrotechnic Society of France (SHF).