Rotating flow in a cylinder with a circular barrier on the bottom

The relative flow of a homogeneous, slightly viscous fluid in a rotating cylinder is induced by differential rotation of the bottom disk, on which a thin circular strip of small height is fixed. The axis of symmetry of the strip coincides with the rotation axis of the cylinder. At the strip a Stewartson layer exists which is partially free, partially attached to the strip. The structure of the Stewartson E1/4-layer E being the Ekman number) is not affected by the height of the strip, but the E1/3-layer problem has to be solved in the two separate intervals. The fact that both solutions do not match at the strip edge necessitates the presence of an intermediate region that exhibits some characteristic features of an Ekman layer.