Effect of interface viscosity on the breakup of liquid sheets

Resumo

Free surface flow is of major relevance in many fluid dynamics applications, both at the macroscopic
scale, like in the study of water waves and the design of watercraft, and at the microscopic scale, such as in thin
films and microfluidics. Understanding the physical mechanisms contributing to the stability of thin liquid sheets
is a challenging problem, as they present a fluid-fluid interface which is free to deform. In systems with high
surface area to volume ratios, such as micro bubbles, blood cells and emulsions, the dynamics of the system are
also highly influenced by the dynamics on the interface. In addition, the presence of surface-active agents such as
polymers and surfactants may lead to complex interfacial rheological behavior. In this work, a computational
investigation of the breakup dynamics of a stationary thin liquid sheet bounded by a passive gas with a viscous
interface is presented. An Arbitrary Lagrangian-Eulerian method (ALE) is used to track the interface position. The
rheological behavior of the interface is modeled by the Boussinesq-Scriven law, and the numerical solution is
obtained through finite element approximation. The results show that the stability of free surfaces is influenced by
surface rheology and that the viscous character of the interface delays the sheet breakup, leading to more stable
films.