Subsonic choked flow in the microchannel

Choked gas flows in the microchannel were studied. With use of the direct simulation Monte Carlo (DSMC) method, a serial of microchannels (length L=10,100,and200μm) was simulated and gained a flow-field evolutional trend with pressure ratio. Also, the effects of the boundary condition setting on the mass flux and static pressure distribution were analyzed during the nonequilibrium flows. It is shown that for the microchannel, the sonic point (Ma=1) only appears at the center point of the outlet section when it is choked. Finally, this paper compares the mass flux between the isothermal limiting Navier-Stokes (NS) and DSMC results, and it is concluded that the limiting NS result can be used to estimate the mass flux when the length of the channel is very long (the ratio of length to height is larger than 1000).