Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Fluid dynamics II

DY 25.3: Talk

Thursday, March 26, 2009, 15:15–15:30, ZEU 118

A phase field model for coalescence of droplets with miscible liquids — •Rodica Borcia and Michael Bestehorn — Lehrstuhl Statistische Physik/ Nichtlineare Dynamik, Brandenburgische Technische Universität Cottbus, Deutschland

We investigate the dynamics of interfaces between droplets of miscible liquids using a phase field model. This application is motivated by recent experimental observations showing that sessile droplets of completely miscible liquids do not instantaneously coalesce after peripheral contact if their contact angles are sufficiently small. Instead, after lateral contact, a microscopically thin liquid bridge connects the droplets and delays the droplet fusion. The droplets exchange liquids through this film, but they remain separated. Only after some time (up to minutes) the droplets finally merge into a single droplet and the fluid comes to rest [1]. The coalescence dynamics is obviously influenced by surface forces (Marangoni effects) and depends on the contact angle. 2D computer simulations are performed in order to understand the mixing behavior of different liquids for low and high contact angles at the solid substrate.

[1] H. Riegler, P. Lazar, Langmuir Vol. 24 (2008) 6395-6398.