RT Journal Article
T1 Natural break-up and satellite formation regimes of surfactant-laden liquid threads
A1 Martínez Calvo, Alejandro
A1 Rivero Rodríguez, Javier
A1 Scheid, Benoit
A1 Sevilla Santiago, Alejandro
AB We report a numerical analysis of the unforced break-up of free cylindrical threads of viscous Newtonian liquid whose interface is coated with insoluble surfactants, focusing on the formation of satellite droplets. The initial conditions are harmonic disturbances of the cylindrical shape with a small amplitude  , and whose wavelength is the most unstable one deduced from linear stability theory. We demonstrate that, in the limit e → 0, the problem depends on two dimensionless parameters, namely the Laplace number, La = ρσ0R¯ /µ2, and the elasticity parameter, β = E/σ0, where ρ, µ and σ0 are the liquid density, viscosity and initial surface tension, respectively, E is the Gibbs elasticity and R¯ is the unperturbed thread radius. A parametric study is presented to quantify the influence of La and β on two key quantities: the satellite droplet volume and the mass of surfactant trapped at the satellite’s surface just prior to pinch-off, Vsat and Σsat, respectively. We identify a weak-elasticity regime, β . 0.05, in which the satellite volume and the associated mass of surfactant obey the scaling law Vsat = Σsat = 0.0042La1.64 for La . 2. For La & 10, Vsat and Σsat reach a plateau of about 3 % and 2.9 %, respectively, Vsat being in close agreement with previous experiments of low-viscosity threads with clean interfaces. For La < 7.5, we reveal the existence of a discontinuous transition in Vsat and Σsat at a critical elasticity, βc(La), with βc →0.98 for La . 0.2, such that Vsat and Σsat abruptly increase at β = βc for increasing β. The jumps experienced by both quantities reach a plateau when La . 0.2, while they decrease monotonically as La increases up to La = 7.5, where both become zero.
PB Cambridge University Press
SN 0022-1120
YR 2020
FD 2020-02-25
LK https://hdl.handle.net/10016/35727
UL https://hdl.handle.net/10016/35727
LA eng
NO A.M.-C. and A.S. thank the Spanish MINECO, Subdirección General de Gestión de Ayudas a la Investigación, for its support through project DPI2015-71901-REDT, and the Spanish MCIU-Agencia Estatal de Investigación through project DPI2017-88201-C3-3-R. These research projects have been partly financed through FEDER European funds. A.M.-C. also acknowledges support from the Spanish MECD through grant FPU16/02562, and its associated programme Ayudas a la Movilidad 2017 during his stay at TIPs–ULB, Brussels. J.R.-R. and B.S. thank the FRS-FNRS for financial support, in particular under the umbrella of the Wolflow project. The authors wish to express their deep gratitude to one anonymous reviewer for making insightful comments, which led to a significant improvement of the present work.
DS e-Archivo
RD 1 sept. 2024