On the non-parallel flow stability of the Blasius boundary layer

Abstract

The influence of boundary layer growth on the flow stability of the Blasius boundary layer is analysed on a rational, large Reynolds number, basis, for small disturbances of fixed frequency. The parallel-flow solution forms the leading term and the non-parallel flow effects emerge in a consistent fashion from the asymptotic expansions. Compared with previous, successive approximation, procedures, the theoretical neutral curve obtained here is much more affected by the non-parallel effects and consequently shows somewhat improved agreement with experimental observations, even though the previous and the present approaches (both of which calculate only a finite number of terms) would be identical if taken to infinitely many terms.