https://doi.org/10.1140/epjs/s11734-025-01879-3
Regular Article
Capillary pinch-off in liquid-in-liquid systems
Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Kandi, 502285, Sangareddy, Telangana, India
Received:
10
July
2025
Accepted:
23
August
2025
Published online:
1
September
2025
We investigate the behavior of a lighter fluid introduced into a quiescent, immiscible ambient liquid under low Reynolds number conditions. Two distinct flow regimes, dripping and jetting, are observed, and this study focuses exclusively on the dripping regime. To investigate the flow dynamics, we employ both numerical simulations and experiments. Axisymmetric simulations are conducted using the Volume-of-Fluid (VOF) method with adaptive mesh refinement to accurately capture interface evolution. The experimental setup uses a refractive index-matched silicone oil–sugar water system, enabling simultaneous Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF) measurements. For the first time, a direct quantitative comparison between simulations and experiments is achieved, revealing excellent agreement in capturing key features, such as droplet pinch-off and neck formation. The temporal evolution of the minimum neck radius follows a power-law scaling, with the exponent varying with the Weber number and deviating from classical air–liquid pinch-off behavior. Additionally, the axial velocity at the neck follows a logarithmic trend with time, independent of the Weber number. At low Weber numbers, the droplet curvature exhibits self-similar scaling, which breaks down at higher Weber numbers due to enhanced advection. These findings highlight key differences in pinch-off dynamics between liquid-in-liquid and classical liquid–air systems.
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© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
