STABILITY OF AXIAL POISEUILLE-COUETTE FLOW BETWEEN CONCENTRIC CYLINDERS

The linear stability of axial parallel Poiseuille-Couette flow in an a nnulus between concentric circular cylinders is considered. Using a lo ng-wave version of the axisymmetric Orr-Sommerfeld equation the stabil ity chart of this flow in the velocity ratio-radius ratio plane is der ived. It is shown that pure sliding Couette flow can become unstable i f the radius ratio is below a specific threshold value. Finally, apply ing the results to other flow geometries, it is shown that the boundar y layer along a slender cylinder can become unstable in a confined reg ion downstream the leading edge only.