Localized shear generates three-dimensional transport

TL;DR

This paper uncovers a new rapid mechanism for three-dimensional fluid transport caused by localized shear, which enhances mixing and chemical reactions by enabling particles to jump between streamlines in flows.

Contribution

It introduces a novel 3D transport mechanism near localized shear that is faster and incompatible with existing Resonance Induced Dispersion, expanding understanding of fluid mixing processes.

Findings

Localized shear induces rapid 3D transport.

Transitions between transport dimensionalities depend on streamline jump magnitudes.

The mechanism is demonstrated in abstract and model fluid flows.

Abstract

Understanding the mechanisms that control three-dimensional (3D) fluid transport is central to many processes including mixing, chemical reaction and biological activity. Here a novel mechanism for 3D transport is uncovered where fluid particles are kicked between streamlines near a localized shear, which occurs in many flows and materials. This results in 3D transport similar to Resonance Induced Dispersion (RID); however, this new mechanism is more rapid and mutually incompatible with RID. We explore its governing impact with both an abstract 2-action flow and a model fluid flow. We show that transitions from one-dimensional (1D) to two-dimensional (2D) and 2D to 3D transport occur based on the relative magnitudes of streamline jumps in two transverse directions.