The flow of liquids in unbounded geometry (i.e. without rigid boundary conditions) is encountered in jets and films. Another example is provided by the drainage of foams under gravity. The latter example has been largely investigated these last years [see e.g. Koehler, 2000; Cox, 2001; Pitois, 2005; Saint-Jalmes, 2006]. Most of previous studies consisted in macroscopic measurements performed at...

The effect of copolymers on the breakup and coalescence of polybutadiene ~PB! drops in polydimethylsiloxane ~PDMS! is studied using a four-roll mill flow cell. Copolymers are produced at the interface by a reaction between functionalized homopolymers. They reduce the interfacial tension and thus enhance breakup; they also inhibit coalescence of drops. Under the conditions of our experiments, th...

By using microfluidic chips, we investigate the stability regarding coalescence of droplet pairs under an electric field as a function of drop separation and ac field intensity. Three different regimes are found: stable, coalescence, and partial merging. From this, we identify the two breaking scenarios of a one dimensional train of droplets: in one case the coalescence front propagates; in the...

In this research, the effect ofmixed salts together with mixed ionic surfactants on dropinterface coalescence time was studied for the system of water (d) / toluene(c) as a model system. Sodium dodecyl sulf...

The coalescence of nearly rigid liquid droplets in a turbulent flow field is viewed as the drainage of a thin film of liquid under the action of a stochastic force representing the effect of turbulence. The force squeezing the drop pair is modelled as a correlated random function of time. The drops are assumed to coalesce once the film thickness becomes smaller than a critical thickness while t...

Coalescence of liquid drops is critical in many phenomena such as emulsion stability, inkjet printing, and coating applications. For sessile drops on a solid surface, the coalescence process is more complicated than the coalescence of drops suspended in a fluid medium as a result of the coupling of the contact line motions to the fluid flow. In this paper, we use video microscopy to track the e...

Image analyzing interferometry is used to study the details of the shapes and coalescence of condensing drops of 2-propanol on a quartz surface. The measured thickness profiles give fundamental insights into the transport processes within the drop and its evolution from asymmetric to symmetric shape. The results show the presence of a thin flat film adjacent to the condensing drops and the adso...