Interactions between pairs of oblique waves in a Bickley jet

We consider the weakly nonlinear spatial evolution of a pair of varicose ob lique waves and a pair of sinuous oblique waves superimposed on an inviscid Bickley jet, with each wave being slightly amplified on a linear basis. Th e two pairs are assumed to both be inclined at the same angle to the plane of the jet. A nonlinear critical layer analysis is employed to derive equat ions governing the evolution of the instability wave amplitudes, which cont ain a coupling between the modes. These equations are discussed and solved numerically, and it is shown that, as in related work for other flows, thes e equations may develop a singularity at a finite distance downstream. (C) Elsevier. Paris.