Compressible gas flow in a long microchannel with square cross section was simulated numerically with a three-dimensional continuum model. The governing equations of the model were solved using a control volume method. A parametric study was conducted for Dh = 1μm, L/Dh ratio of 200 and with varying pressure ratio (PR = 1.5 - 5.0). The gas used was nitrogen. Numerical model was validated with available experimental and numerical results. It was found that as the pressure ratio increased from 1.5 to 5.0, compressibility effects increased while the rarefaction effects started diminishing. The slip effects play an important role in the friction characteristics of microchannel flows. Analytical expressions were evaluated on the basis of flow behavior.
