Ekman boundary conditions for numerical models of centrifuge flows

The boundary layers which form on the ends of a gas centrifuge have received a great deal of analytical attention in predicting flows within gas centrifuges. Three basic approaches were taken in estimating the heat transfer and drag at the solid gas interfaces at the ends of a centrifuge. First, the details of the flow may be estimated numerically using finite difference techniques and a very fine grid in the vicinity of the ends. The cost in computer time and memory charges is great and the extensive detail is difficult to utilize effectively. Second, the boundary layers may simply be ignored. With this approach, the size of the finite difference mesh is controlled by other considerations which allow economically attractive simulation of centrifuge flows for many situations. The third effort is to model the boundary layers analytically and couple those models to solutions for the interior flow. Previous efforts to model the the boundary layers are reviewed.