1. Dynamics of Fluids, Department of Experimental Physics, Saarland University, 66123 Saarbrücken, Germany
2. Helmholtz Institute Erlangen-Nürnberg for Renewable Energy, Forschungszentrum Jülich, 91058 Erlangen, Germany
3. Department of Chemical and Biological Engineering and Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
4. Department of Physics and Materials Science, University of Luxembourg, 1511 Luxembourg City, Luxembourg