Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Breakup of two-layer liquid film
Submission Author:
Pedro Calderano , MG
Co-Authors:
Pedro Calderano, Marcio CARVALHO
Presenter: Pedro Calderano
doi://10.26678/ABCM.COBEM2021.COB2021-0219
Abstract
Thin liquid sheets are present in a variety of systems and applications, including curtain coating process. One of the most important process limits is the curtain breakup, which sets a lower limit for the coating liquid flow rate. Consequently, this lower limit flow rate defines the minimum possible thickness of the deposited film. Experimental evidences have shown that using a two-layer curtain with a highly viscoelastic thin layer may delay the curtain breakup, allowing coating of thinner films. The optimization of the two-layer curtain process with the goal of reducing the minimum flow rate is not fully understood. In the present work, we study the breakup of two-layer liquid sheets, composed of a Newtonian and a viscoelastic liquid, by solving the set of differential equations that describe this free boundary problem. The model is derived from the basic hydrodynamic equations using a longwave approximation and the resulting set of differential equation is solved by the finite difference method. We investigate the effect of different process parameters and liquid properties on the breakup time. The results show how the viscoelastic forces delay the breakup, stabilizing the liquid sheet.
Keywords
Non-Newtonian fluid, viscoelastic fluid, thin film, Curtain coating, double-layered sheets
