Plane Poiseuille-Couette problem in Micro-Electro-Mechanical Systems applications with gas-rarefaction effects.

Rarefied gas flows in micro-electro-mechanical systems (MEMS) devices, calculated from the linearized Bhatnagar-Gross-Krook model equation, are studied in a wide range of Knudsen numbers. Both plane Poiseuille and Couette flows are investigated numerically. Moreover, a variational approach, applied to the integrodifferential form of the linearized Boltzmann equation, is used to solve in a unified manner the plane Poiseuille-Couette problem by means of the computation of only one functional. General boundary conditions of Maxwell's type have been considered, assuming both symmetric and nonsymmetric molecular interaction between gas-solid interfaces, in order to take into account possible differences in the accommodation coefficients on the walls of MEMS devices. Based on the analysis presented in this paper, an accurate database valid in the entire Knudsen regime can be created for the Poiseuille-Couette problem, to be used in micromechanical applications.