Linear and Secondary Instabilities in Incompressible Axisymmetric Boundary Layers: Effect of Transverse Curvature By N.V INODand RAMA GOVINDARAJAN

The stability of the incompressible boundary layer in the axial flow past a cylinder has not been studied a great deal. The laminar flow is shown here to be always stable at high transverse curvatures to linear as well as secondary disturbances. At low levels of curvature, the first instability is delayed, but several non-axisymmetric modes are simultaneously unstable, which could lead to a different breakdown to turbulence. This prediction, as well as the envisaged downstream relaminarisation of turbulent flow especially on relatively thin bodies, lend themselves to experimental and numerical verification. The flow is shown to be inviscidly stable at any curvature.