Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 38: POSTERS Micro- and Nanofluidics
CPP 38.13: Poster
Donnerstag, 26. März 2009, 17:00–19:30, P3
Stability of droplets: A free energy based lattice Boltzmann study — •Markus Gross1,2, Fathollah Varnik1,2, and Dierk Raabe1 — 1Max-Planck Institut für Eisenforschung, Düsseldorf, Germany — 2Interdisciplinary Center for Advanced Materials Simulation, Ruhr-Universität Bochum, Germany
Liquid droplets are very important in many scientific research branches and their study has attracted much interest for a long time. In this work we investigate the behavior of droplets via a mesoscale computer simulation approach, the Lattice Boltzmann method.
In the first part, we consider the stability of a droplet and its saturated vapor inside a finite volume, an issue of considerable importance in nanotechnology. Results obtained within our simulations show the same system size dependence as obtained via analytic approximations to the underlying free energy functional as well as independent numerical solutions of the problem. In particular, we find a certain critical radius below which a liquid droplet becomes unstable and evaporates.
A second topic of fundamental interest is the behavior of droplets on superhydrophobic substrates for the case where the droplet is of comparable size to the roughness scale. A simple analytical free energy model is presented that can explain all the essential results of our simulations. Most interestingly, we are able to observe a new generic metastable state of partial impalement that is different from the known Cassie/Baxter or Wenzel states. Furthermore, we study the stability of the Cassie/Baxter state and its dependence on the substrate geometry, contact angle and droplet size.