# Influence of two breakup models on the droplet behavior in a cellular gaseous detonation

Hiroaki Watanabe, Ashwin Chinnayya, Said Taileb

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Hiroaki Watanabe, Ashwin Chinnayya, Said Taileb. Influence of two breakup models on the droplet behavior in a cellular gaseous detonation. International conference on numerical combustion 2025, Oct 2025, Rome, Italy. hal-05400051

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Submitted on 5 Dec 2025

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# Influence of two breakup models on the droplet behavior in a cellular gaseous detonation

Hiroaki Watanabe¹*, Ashwin Chinnayya¹, Said Taileb²

¹ Institut Pprime - UPR 3346 - CNRS - ISAE-ENSMA - Université de Poitiers, 1 Avenue Clément Ader, BP 40109, 86961, Futuroscope-Chasseneuil Cedex, France

² Safran Tech, Magny-Les-Hameaux, France

Simulations of two-phase detonation, such as those presented in [1], often rely on a breakup model based on simplified assumption, such as a linear decrease in the droplet diameter [2]. However, large droplets can produce small droplets through mechanisms such as shear induced entrainment (SIE) and Rayleigh-Taylor Piercing [3,4], rendering this simplified assumption in-accurate. Additionally, a distribution of droplet diameter after the breakup process is expected [5]. The size of these droplets is closely linked to the time scales associated with heating, evaporation, breakup, and velocity relaxation. Consequently, any changes in the prediction of the droplet diameter after the breakup can significantly influence the dynamics of two-phase detonation.

The study evaluates the influence of breakup model on the behavior of a droplet in a cellular gaseous detonation. To efficiently compare the droplet behavior under two distinct breakup models, we employed a one-way coupling approach. This method was chosen to specifically isolate the effect of the flow fields on droplet dynamics.

This preliminary work will compare the results obtained from two different breakup models. The first model operates under simplified assumption that the droplet diameter changes linearly during the breakup process. In contrast, the second model incorporates two distinct peaks in the diameter distribution.

First results will be communicated at the conference.

## References

[1] Watanabe H., Matsuo A., Chinnayya A., Matsuoka K., Kawasaki A., and Kasahara J. Numerical analysis on behavior of dilute water droplets in detonation. *Proceedings of the Combustion Institute*. 2021;38:3709-3716.

[2] Chauvin A., Daniel E., Chinnayya A., Massoni J., and Jourdan G. Shock waves in sprays: numerical study of secondary atomization and experimental comparison. *Shock Waves*. 2016;26:403-415.

[3] Theofanous T. G. Aerobreakup of Newtonian and viscoelastic liquids. *Annual Review of Fluid Mechanics*. 2011;43:661-690.

[4] Dorschner B., Biasiori-Poulanges L., Schmidmayer K., El-Rabii H., Colonius T. On the formation and recurrent shedding of ligaments in droplet aerobreakup. *Journal of Fluid Mechanics*. 2020;904:A20.

[5] Park J. E. and Lee T. W. Shock-induced drop size and distributions. *Combustion and Flame*. 2025;275:114091.

<footnote>*Lead presenter: hiroaki.watanabe@ensma.fr</footnote>