Fig. 4

The system MFP of a gas varies as the function of Kn using MD (open circles): λ_s and λ₀ are the system MFP and the nominal MFP, respectively. An exponential fit can be expressed as λ_s(Kn)/ λ₀ = 0.255 + 0.784 exp(-Kn/1.122) (the dotted line). The system MFPs in nanochanels obtained in MD simulations by Barisik and Beskok [28] (filled green diamond) and Perumanath Dharmapalan et al [29] (filled red squares) are also shown for comparison. Note that Kn was kept a constant by changing both the density of gas and channel height in [28], and the range of the channel height varied only from 6 nm to 16 nm in [29]