Berlin 2008 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: POSTERS Driven Soft Matter
CPP 20.4: Poster
Wednesday, February 27, 2008, 16:00–18:30, Poster A
Bouncing Droplets and Partial Coalescence with Polymer Solutions — •Stephan Gier1, Stéphane Dorbolo2, and Christian Wagner1 — 1Technische Physik, Universität des Saarlandes, D-66123 Saarbrücken — 2GRASP, Université de Liège, B-4000 Liège
We investigate bouncing droplets consisting of different polymer solutions on a vibrated Newtonian liquid surface. It is known that Newtonian liquid droplets on a vibrated bath of a high viscosity oil undergo a bouncing motion. In our experiments we see that adding different polymers or surfactants changes the bouncing behaviour of the droplets. This holds for both the shape of the droplets and the acceleration threshold of the vibrated bath. If one puts a liquid droplet on an interface between two fluids, where the lower one is the same as the droplet fluid, then partial or total coalescence can occur depending on four dimensionless parameters (Bond number, Ohnesorge numbers of both fluids, relative density difference between the two fluids). This is well known for Newtonian liquids. For our non-Newtonian solutions the coalescence is only nearly partial in all the experiments because the elasticity of the polymer solutions suppresses the forming of a so-called daughter droplet.