Turbulent oscillation in unbalanced T-junction flows

TL;DR

This paper uncovers a new oscillatory turbulence mode in high-Reynolds-number unbalanced T-junction flows, with implications for fluid mixing and nanoparticle production.

Contribution

It introduces the discovery of a novel oscillatory behavior and turbulence-production mode in unbalanced T-junction flows through high-fidelity simulations.

Findings

Identified a new oscillatory behavior between inlet streams.

The oscillation persists across various Reynolds numbers with a constant Strouhal number.

Fluid parameters follow a power-law relation with Reynolds number.

Abstract

The T-junction impinging flow occurs in many fluid dynamics systems. In particular, the T-junction micromixer has recently been widely used for nanoparticle production, where the two inlet streams operate at a significant flow-rate imbalance and the Reynolds number is in the turbulent regime. This operating condition exposes a gap in the existing literature on the fluid dynamics of the T-junction. In this study, we used high-fidelity numerical simulations to investigate high-Reynolds-number unbalanced T-junction flows. We discover a new oscillatory behavior between the two inlet streams at the T-junction, leading to a new turbulence-production mode. We will present detailed evidence of this new behavior, in contrast to the existing understanding of balanced turbulent T-junction flows. This oscillatory behavior also persists across a range of Reynolds numbers simulated, where the Strouhal number is approximately constant, indicating a self-similar phenomenon. As a result, many of the fluid dynamics parameters follow a power-law relation with the Reynold number. The discovery in this paper affects real-world applications, where process design and product quality are affected by turbulence and mixing dynamics.