Computational and experimental analysis of dynamics of drop formation

Citation
Ed. Wilkes et al., Computational and experimental analysis of dynamics of drop formation, PHYS FLUIDS, 11(12), 1999, pp. 3577-3598
Citations number
57
Categorie Soggetti
Physics
Journal title
PHYSICS OF FLUIDS
ISSN journal
10706631 → ACNP
Volume
11
Issue
12
Year of publication
1999
Pages
3577 - 3598
Database
ISI
SICI code
1070-6631(199912)11:12<3577:CAEAOD>2.0.ZU;2-7
Abstract
Dynamics of formation of a drop of a Newtonian liquid from a capillary tube into an ambient gas phase is studied computationally and experimentally. W hile this problem has previously been studied computationally either (a) us ing a set of one-dimensional equations or (b) treating the dynamics as that of irrotational flow of an inviscid fluid or creeping flow, here the full nonlinear, transient Navier-Stokes system subject to appropriate initial an d boundary conditions is solved in two dimensions to analyze the dynamics a t finite Reynolds numbers. The success of the computations rests on a finit e element algorithm incorporating a multiregion mesh which conforms to and evolves with the changing shape of the drop. The new algorithm is able to c apture both the gross features of the phenomenon, such as the limiting leng th of a drop at breakup and the volume of the primary drop, and its fine fe atures, such as a microthread that develops from a main thread or a neck in a viscous drop approaching breakup. The accuracy of the new calculations i s verified by comparison of computed predictions to old and new experiments . With the new algorithm, it is shown for the first time that the interface of a viscous drop can overturn before the drop breaks. Calculations have a lso been carried out to determine the range of parameters over which algori thms that treat the drop liquid as inviscid and the flow inside it as irrot ational can accurately predict the dynamics of formation of drops of low vi scosity liquids. Limiting lengths of drops and primary drop volumes are com puted over a wide range of the parameter space spanned by the relevant dime nsionless groups. (C) 1999 American Institute of Physics. [S1070-6631(99)01 812-7].