Effects of the centrifugal forces on a gas between rotating cylinders

The gas e ow between two concentric rotating cylinders is investigated over a wide range of governing dimensionless products. Analytic solutions are given for the free molecular e ow, for the Bhatnagar ‐Gross‐Krook model up to the e rst-order approximation, and for the hydrodynamic limit in the Chapman ‐Enskog expansion. The slip e ow boundary conditionsareextensively discussed, and a constructivesolution to the transitional e ow is proposed. Numerical direct simulation data are obtained and adopted as exact reference experimental results.