Absolute/convective secondary instabilities and the role of confinement in free shear layers

TL;DR

This paper investigates how confinement influences the growth and wavelength selection of free shear layers using a point vortex model, revealing the limiting effects of confinement on vortex pairing and layer development.

Contribution

It introduces a wavelength selection mechanism for free shear layers with counterflow, highlighting the role of confinement in limiting vortex pairing growth.

Findings

Confinement limits vortex pairing in shear layers.

A wavelength selection mechanism is proposed.

Confinement influences the self-similar growth of mixing layers.

Abstract

Mixing layers can grow in time or space by vortex pairings that succeed each other in a nearly self-similar way. We use a point vortex model to study how confinement eventually limits this growth process, leading us to propose a wavelength selection mechanism for free shear layers with counterflow.