Exit region central source flow between finite closely spaced parallel co-rotating disks

Laminar source flow between co-rotating disks can often be adequately described by boundary layer equations. However, when the disk spacing and rotation speed are large (small Ekman number) and the source strength is small (small Rossby number), recirculation occurs near the edges of the disks and the boundary layer equations cannot correctly describe the flow there. The flow is studied in the vicinity of the disk edges for swirl Reynolds number of order 106 using approximate equations that are valid in a small region far from the rotation center. Numerical solutions are obtained by finite differences for three values of the Ekman number E and several values of the Rossby number ε. The Ekman numbers chosen give flows between the disks characterized by linearized theory, boundary layer theory, and rotating flow theory with Ekman layers.