We utilized DSMC method to investigate the effectiveness of NSF equations in the slip and transient rarefaction regimes. Monatomic argon confined in a micro/nano lid-driven cavity is considered in this study. Full NSF equations accompanied by first and second order slip velocity and temperature jump boundary conditions are used to capture non-equilibrium phenomenon. It is seen that although velocity profiles are predicted quite accurately by means of proper slip boundary conditions, NSF equations fail to predict correct shear stress distribution and heat flux direction even in the middle slip regime. It is also seen that applying second order velocity slip boundary condition in the transient regime reduces the accuracy of the continuum approach. Fourier law, which only assumes the temperature gradients for direction of the heat flux, loses its validity in the slip regime and beyond.

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