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arXiv · 2610.29193

Dynamics of liquid jet breakup and droplet size distribution in a crossflow airstream

Gowri Padmaja Majji·Aman John Tudu·Lakshmana Dora Chandrala·Kirti Chandra Sahu
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Abstract

The fragmentation of a liquid jet in a crossflowing airstream arises from a complex interplay between aerodynamic forcing and interfacial instabilities acting across a wide range of length scales. We examine the spatial evolution of droplet size distributions along the jet trajectory using a combination of high-speed shadowgraphy and digital in-line holography, allowing simultaneous characterization of jet morphology and volumetric droplet size distributions. The results demonstrate a clear progression of breakup mechanisms, from near-field bag rupture to downstream rim, ligament, and node disintegration, each associated with distinct characteristic length scales. This evolution is reflected in the droplet size distributions, which broaden and become increasingly polydisperse downstream relative to the near-field distributions. By systematically varying the liquid-jet and airstream Weber numbers, we identify distinct breakup modes, and construct a regime map that delineates the column-breakup, isolated-bag-breakup, and interacting-bag regimes. Furthermore, by incorporating the dominant instability mechanisms, including Rayleigh-Taylor and Rayleigh-Plateau instabilities associated with the observed column, bag, and multi-bag breakup modes, we develop a theoretical framework for jet atomization in crossflow. The framework relates instability wavelengths to characteristic droplet sizes, and reasonably captures the experimentally observed trends. We found that stronger aerodynamic forcing induces earlier breakup, decreases the characteristic instability length scales, and generates finer droplets dispersed over a wider spatial region. Overall, the study establishes a quantitative relationship between instability-driven fragmentation dynamics and droplet size distributions, thereby connecting interfacial instabilities with measurable spray characteristics.

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Gowri Padmaja Majji, Aman John Tudu, Lakshmana Dora Chandrala, Kirti Chandra Sahu. 2026-10-21. Dynamics of liquid jet breakup and droplet size distribution in a crossflow airstream. https://arxiv.org/abs/2610.29193

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