Solutions to the mass transfer problem in a gas centrifuge are examined as a function of source‐sink geometry. The model centrifuge consists of a pair of concentric circular cylinders bounded on the top and bottom by horizontal end plates; the apparatus rotates rapidly about the axis of the cylinders. During steady operation, a binary gas mixture containing species A and B is injected into the container through small axisymmetric slots located on the sidewalls. Solutions for the concentration field within the centrifuge are obtained formechanicallyorthermallydriven centrifuges; maximum values of the separation factor based on product and feed mass fractions are predicted as a function of feed, product, and waste port locations. Both moderate and strongly forced flows in the container are considered.