A Window onto Turbulence: Harnessing Eddies for Selective Functionality

Turbulence is widely known for its chaotic nature, often leading to rapid mixing and unpredictable motion. The Richardson cascade provides a framework for understanding the steady-state structure of turbulent flow as a soup of eddies. We explore methods for creating sharp gradients in turbulent intensity—bridging the gap between quiescence and fully developed turbulence—using appropriately shaped particles. We show that these gradients can be leveraged to induce highly selective and directional particle transport, that works, in experiment, from the cm scale to the micrometre scale. Remarkably, turbulence can act simultaneously as both a mixing agent and a sorting mechanism—concentrating certain particles while excluding others—despite its inherent disorder. Our findings reveal a surprising and functional aspect of turbulence, with potential implications for engineered transport, environmental sensing, and controlled delivery in complex fluid environments.