Can aerosols be trapped in open flows?

TL;DR

This paper demonstrates that aerosols can be permanently trapped in open flows due to flow vortices, challenging the common assumption that they always escape, with implications for various physical contexts.

Contribution

It reveals that aerosols heavier than the fluid can be permanently trapped in open flows, a behavior not previously recognized, across different flow dynamics and gravitational conditions.

Findings

Aerosols can be permanently trapped in open flows.

Trapping occurs due to multiple vortices in the flow.

This phenomenon applies to realistic particle-fluid density ratios.

Abstract

The fate of aerosols in open flows is relevant in a variety of physical contexts. Previous results are consistent with the assumption that such finite-size particles always escape in open chaotic advection. Here we show that a different behavior is possible. We analyze the dynamics of aerosols both in the absence and presence of gravitational effects, and both when the dynamics of the fluid particles is hyperbolic and nonhyperbolic. Permanent trapping of aerosols much heavier than the advecting fluid is shown to occur in all these cases. This phenomenon is determined by the occurrence of multiple vortices in the flow and is predicted to happen for realistic particle-fluid density ratios.