Unsteady gaseous flows in rectangular microchannels: frequency response of one or two pneumatic lines connected in series

This paper represents an initial analysis of unsteady gaseous Bows in a rectangular microchannel under usual pressure and temperature conditions. The effect of depth and aspect ratios of the cross-section is investigated. With most fluid-based mechanical microsystems of snail internal dimensions and subject to normal pressure and temperature conditions, flow is rarefied with slip at the walls. This flow is then modeled by the Navier-Stokes equations combined with slip and temperature jump conditions at the walls. These conditions are represented by Maxwell-Smoluchowski first order equations. By concentrating essentially on the pulsed sinusoidal regime, it is shown that the instantaneous flow rate amplitude, as well as the band pass of the microchannel are underestimated when slip at the walls is not taken into account. The frequency response of two microchannels connected in series with different cross-sectional areas is also studied. Finally, the proposed model can serve as a tool giving information about the current feasibilities of pressure sensors for the measurement of the dynamic characteristics of gaseous flows in microchannels. (C) Elsevier, Paris.