Poiseuille and Couette flows in plane nanochannels with crystalline and amorphous walls are considered. The effect of the vibrating walls on the Poiseuille flow was also considered. As a result, the velocity profiles of the fluid and its effective viscosity and the time dependence of the moving wall friction force were obtained for several magnitudes of the fluid flow velocities. On the basis of Fourier and wavelets analysis of the friction force time dependence one can conclude that: the periodic components of the friction force with the period proportional to the period of the crystalline structure correspond to periodic structure in the fluid induced by the channels walls; there is a periodic process of the initiation of the domains of a fluid structure failure; there is a wave process across the channel. On the basis of the molecular dynamic simulations and experimental data taken from the literature the governing equations which describe the fluid behaviour in the above mentioned flat nanochannels (of 5? 20 nanometers size) are presented. The above equations provide a possibility to describe the observed effects in the fluid on the basis of continuum mechanics. The fluid model is a 2 phase fluid model. The one of the continuums corresponds to the new phase which can appear in the fluid flow in nanosized flat nanochannels. The critical magnitude of the two-phase fluid density which corresponds to the locking of the channel was found with the help of the suggested equations.
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