Molecular Dynamics Simulations of Retraction and Rupture of Liquid Sheets

Liquid sheets are encountered in a wide variety of natural and industrial processes. Some important examples in which a fundamental understanding of the dynamics of liquid sheets is critical include processes involved in applying coatings and paints, operation of fuel injection systems, biological membranes, bubble and droplet coalescence in foams and emulsions, and crop spraying. Not surprisingly, the retraction and rupture of liquid sheets has been a topic that has been extensively studied using continuum mechanics. In a liquid sheet, which is bound by two free surfaces, the balance between inertia and surface tension and viscous forces determines the dynamics of retraction and rupture. Depending on the application, the rupture and fragmentation of liquid sheets can either be desirable, e.g. atomization, or undesirable, e.g. curtain coating. In this study, we use molecular dynamics (MD) simulations to probe the problem on length and time scales that are much smaller than those over which the continuum assumption holds. Here, we use MD to carry out a detailed study of the rate of retraction liquid sheets. Moreover, we also explore the role played by thermal fluctuations on the liquid surface(s) in driving sheet rupture and propose an order of magnitude analysis for the same.