Fast liquid sheet and filament dynamics in the fluid splitting process

Publication date: Available online 1 June 2018Source: Colloids and Surfaces A: Physicochemical and Engineering AspectsAuthor(s): Hans Martin Sauer, Ilia V. Roisman, Edgar Dörsam, Cameron TropeaAbstractWe consider the fluid splitting dynamics of a small fluid drop entrapped between two parallel solid plates, which are rapidly pulled apart such that a free liquid sheet is formed between them for a few milliseconds. Velocities, time scales and shear rates correspond to the lift-off of a printing cylinder from the substrate in an industrial printing process.The formation and collapse of the liquid sheets, and the filaments forming at their rim are studied. Driven by the surface tension of the liquid sheet, the filaments are accelerated towards each other, and finally collide and decay. We show that surface waves that travel on the liquid sheet have a critical impact on this collision, which may either result in a smooth unification or in a highly dynamical collapse, ending in a random emission of fluid drops. Furthermore, we discuss the relevance of the Laplace number on the propagation of these waves.We also consider the liquid sheet decay by capillarity-driven expansion of spontaneously forming holes and discuss how sheet thickness and its local variation can be detected by an anisotropic hole expansion rate measurement.Graphical abstract

Source: Colloids and Surfaces A: Physicochemical and Engineering Aspects - July 11, 2018 Category: Chemistry Source Type: research