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Poiseuille and thermal creep flows between two walls, on which grooves are engraved periodically parallel or normal to the pressure or temperature gradient, are investigated numerically using the linearized B-G-K equation. It is found that the flux between two walls is considerably low compared with that of a flat wall when both groove width and pitch are rather small compared with its depth. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

To investigate flow of gas mixtures through micro channel in detail, the tangential momentum accommodation coefficients of each species for gaseous mixtures were determined by analyzing the Couette flow problem of a slightly rarefied gas between two walls. The molecular dynamics (MD) method for the interaction of gas molecule with the wall surface is combined with the DSMC method for the motion of gas molecules. These obtained accommodation coefficients were applied for the flow of gas mixture through the micro channel as the Maxwell-type boundary conditions, and influence of the surface with adsorbates and the gas concentration on the flow rate of the micro channel was examined. The simulation results show that the velocity slip and the accommodation coefficients for gas mixtures differ from that for a single gas. The differences of the molar concentration of gas mixtures and wall characteristics lead to variations of the flow rate in the channel. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The molecular dynamics method for the interaction of the gas molecule with the solid wall together with the Monte-Carlo method for the motion of gas molecules is applied to analyze the behavior of a slightly rarefied gas between two walls. The wall consists of platinum molecules and the gas is taken to be xenon or argon. The Couette flow and the thermal problem for which two walls have different temperature are considered. The slip or jump coefficient of the flow and the accommodation coefficient of the tangential momentum, normal momentum or kinetic energy are obtained at the wall of 300K temperature. The distribution function of the molecule at the wall surface is also obtained, and it is found that the Maxwell type boundary condition describes well the distribution function of the reflected molecule. [ABSTRACT FROM AUTHOR]