On the development of noise-producing large-scale wavelike eddies in a turbulent jet

The development of large-scale wavelike eddies in a two-dimensional turbulent jet was studied. The basic mean flow develops from a mixing region type with an initial specified boundary layer thickness into a fully developed jet. The role of the varicose and sinuous modes as these develop in a growing mean flow is brought out. In general, it was found, for a given frequency parameter, the varicose mode has a shorter streamwise lifetime than the sinuous mode. The latter, for lower frequency ranges, persists past the end of the potential core only to be subject to dissolution by the more enhanced fine scale turbulent activity in that region.