Chaotic self-sustaining structure embeded in turbulent-laminar interface

TL;DR

This paper investigates a localized, self-sustaining structure at the turbulence-laminar interface in 2D channel flow, revealing its role in generating turbulence and inhomogeneity through a novel 'ejection-jet' cycle model.

Contribution

It introduces a new understanding of the self-sustaining, functional structure at the turbulence-laminar interface and models its multiscale dynamics with a phenomenological cycle.

Findings

The structure actively converts laminar flow into turbulence.

The dynamics are characterized by an 'ejection-jet' cycle.

The structure sustains itself through multiscale interactions.

Abstract

An iterface structure between turbulence and laminar flow is investigated in two-dimensional channel flow. This spatially localized structure not only sustains itself, but also converts laminar state into turbulence actively. In other words, this coherent structure has a functionality to generate inhomogeneity by its inner dynamics. The dynamics of this functional coherent structure is isolated using the filtered simulation, and a physical perspective of its dynamics is summarized in a phenomenological model called an "ejection-jet" cycle, which includes multiscale interaction process.