Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Mixing Behavior of Absolutely Unstable Axisymmetric Shear Layers Forming Side Jets



William M. Pitts, A W. Johnson


Recently it has been shown that low-density axisymmetric jets can become absolutely unstable and develop highly coherent vortical structures in the near-field shear layer. These jets have several unusual properties when compared to jets which are convectively unstable. The vortical structures grow quickly with downstream distance and rapidly develop three-dimensional structure. Intense pairing of alternative structures is observed. Perhaps the most interesting of all behaviors is the observation of strong ejections of jet fluid, termed "side jets", into the ambient surroundings. Their formation is attributed to the generation of strongly coupled pairs of lontiudinal vortices in the developing shear layer.
Fluid Mechanics and Its Applications


absolute instability, axisymmetric jets, concentration measurement, mixing, Raleigh light scattering, side jets


Pitts, W. and Johnson, A. (1997), Mixing Behavior of Absolutely Unstable Axisymmetric Shear Layers Forming Side Jets, Fluid Mechanics and Its Applications, [online], (Accessed April 19, 2024)
Created January 1, 1997, Updated February 19, 2017