On two-dimensional laminar wakes and jets

Abstract

The flow fields in two-dimensional, isoenergetic, viscous free mixing with constant β and with initial velocity profiles deviating slightly from those given by wakelike solutions of the Falkner-Skan equation for that β are considered. The similar solutions of the Falkner-Skan equation are investigated in more detail than in the past, e.g. we show that as β → −1 the flows approach the pure jet with the surrounding fluid at rest, and that there are new branch solutions for β < −1. We have investigated the spatial stability of these flows; it is found that for β > − 0·5 the only spatially stable solutions are the trivial ones f′(η) ≡ 1, but for −1 < β < − 0·5 there are non-trivial, jet-like solutions which are spatially stable. As to the new branch solutions for β < − 1, all are spatially unstable.