VISCOUS INTERACTION BETWEEN PARALLEL RADIAL STREAMS

Similarity solutions of the appropriate boundary-layer equations are o btained for the steady laminar shear layer between adjacent parallel r adial streams of different velocities. The dependence of the resulting velocity distributions upon the radial pressure gradient is investiga ted. A minimal favourable pressure gradient is necessary for inward ra dial flows to produce shear layers of finite displacement thickness. T he latter requirement determines a unique solution in the case of outw ard flows. The maximal adverse pressure gradient for which the present problem admits of physically acceptable similarity solutions is signi ficantly larger than the corresponding value for boundary layers on a solid wall.