Nonuniformities in miscible two-layer two-component thin liquid films

Christopher Larsson, Satish Kumar

Research output: Contribution to journalArticlepeer-review

Abstract

Depositing and obtaining a liquid film of uniform thickness is a problem integral to numerous applications and requires an understanding of capillary leveling, Marangoni flows, evaporation, and various other phenomena. These applications often demand multilayer films where each layer has distinct properties, and this gives rise to additional challenges. It has been experimentally demonstrated that two-layer films in which the layers are miscible can undergo dewetting, but theoretical understanding of this phenomenon is lacking. Through a lubrication-theory-based model, this work studies the mechanisms that may initiate dewetting in miscible two-layer two-component films. The model film consists of nonvolatile solvent and solute with constant density and viscosity. Two coupled fourth-order nonlinear partial differential equations describing the time evolution of the film height and solute concentration are derived and then solved with a pseudospectral method. It is found that a disparity in initial solute concentration between the film layers drives flows that lead to significant film-height nonuniformities. A parametric study is conducted to examine the influence of system parameters on this behavior and to develop several scaling relations that shed light on the underlying physical mechanisms.

Original languageEnglish (US)
Article number034004
JournalPhysical Review Fluids
Volume6
Issue number3
DOIs
StatePublished - Mar 2021

Bibliographical note

Funding Information:
This work was supported by the Industrial Partnership for Research in Interfacial and Materials Engineering of the University of Minnesota. We also acknowledge partial support through a fellowship awarded to C.L. by the PPG Foundation.

Publisher Copyright:
© 2021 American Physical Society.

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