Controlling the breakup of spiralling jets: results from experiments, nonlinear simulations and linear stability analysis

Kamis, Y.E.; Prakash, Suriya; Breugem, W.P.; Eral, H.B.

doi:10.1017/jfm.2023.31

Controlling the breakup of spiralling jets

Title

Controlling the breakup of spiralling jets: results from experiments, nonlinear simulations and linear stability analysis

Author

Kamis, Y.E. (TU Delft Multi Phase Systems)
Prakash, Suriya (TU Delft Complex Fluid Processing)
Breugem, W.P. (TU Delft Multi Phase Systems)
Eral, H.B. (TU Delft Complex Fluid Processing)

Date

2023

Abstract

We experimentally and numerically study the dynamics of a liquid jet issued from a rotating orifice, whose breakup is regulated by a vibrating piezo element. The helical trajectory of the spiralling jet yields fictitious forces varying along the jet whose longitudinal projections stretch and thin the jet, affecting the growth of perturbations. We show that by quantifying these fictitious forces, one can estimate the jet intact length and size distribution of drops formed at jet breakup. The presence of the locally varying fictitious forces may render high-frequency perturbations, that would otherwise be stable in the abscence of stretching, unstable, as observed similarly in the case of straight jets stretching under gravity. The perturbation amplitude then dictates how strong the perturbation is coupled to the jet compared with random noise that is inherently present in any experimental set-up. In the present study we exploit the slenderness of the jet to separate the calculation of the base flow and the growth of perturbations. The fictitious forces calculated from the base flow trajectory are then used in a nonlinear slender-jet model, which treats the spiralling jet as a quasi-straight jet with locally varying body forces. We show both experimentally and numerically that jet breakup characteristics (e.g. intact length and drop size distribution) can be controlled by finite-amplitude perturbations created by mechanically induced pressure modulations. Finally, we revisit the integrated net gain approach developed for straight jets under gravity and we provide simple analogous relations for spiralling jets.

Subject

instability control
nonlinear instability
breakup/coalescence

To reference this document use:

http://resolver.tudelft.nl/uuid:fc0820da-9c4a-4f15-ba94-98c408a40a47

DOI

https://doi.org/10.1017/jfm.2023.31

ISSN

0022-1120

Source

Journal of Fluid Mechanics, 956

Part of collection

Institutional Repository