A solution of the problem of Poiseuille slip flow through an eccentric cylindrical annulus is obtained in bipolar coordinates. The solution is in excellent agreement with the two published limiting cases of slip flow through concentric annuli and no-slip flow through eccentric annuli. It is shown that for a fixed aspect ratio, fully eccentric channels sustain the maximum average velocity (flow rate) under the same pressure gradient and slip conditions. For a given channel geometry, the average velocity varies linearly with Knudsen number except for small aspect ratio. It is also shown that the extrema of the friction factor Reynolds number product is determined by how this product is defined or scaled.
A simple solution of the problem of inviscid flow past two circular cylinders is presented. The two cylinders may be of different diameters and located at any distance from each other. The solutions of the two main cases, namely, when the flow is perpendicular to the center-to-center line and when the flow is parallel to it (tandem cylinders), lead to a solution of the problem when the flow is in an arbitrary direction.