Regensburg 2013 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 27: Fluid Dynamics and Turbulence
DY 27.6: Vortrag
Donnerstag, 14. März 2013, 11:00–11:15, H48
Droplet impact on free-standing smectic liquid crystalline films — •Sarah Dölle1, Thomas John1,2, and Ralf Stannarius1 — 1Department of Nonlinear Phenomena, Faculty of Science, University of Magdeburg, PB 4120, 39016 Magdeburg, Germany — 2Department of Experimental Physics, Faculty of Science, University of Saarland, 66123 Saarbrücken, Germany
Liquid droplet impact on solid and liquid surfaces, including wetting phenomena and splashing behavior have been in the focus of scientific interest since decades. Experimental and theoretical work so far dealt basically with droplets hitting wet solid substrates, dry solid substrates or deep liquid pools. Mostly, the diameters of the droplets were chosen in the millimeter range. With the development of inkjet printing, however, a strong interest in the impact behavior of picoliter droplets emerged. So far, only few investigations have been carried out on droplet collisions with free-standing liquid films. We present a study on the impact of aqueous droplets with a diameter of about 50 microns on freely suspended, smectic liquid crystalline films. Because of the small dimensions of the droplets, the Weber and Ohnesorge numbers, that describe the ratios of inertial, viscous and surface tension related forces, are smaller than one. In this regime, capillary forces prevail over kinetic effects and viscous forces. Smectic liquid crystals are favorable materials to generate free-standing films. Due to their layered molecule structure, these films remain stable even if the thickness is as low as two molecular layers. The impact process was resolved via high-speed imaging, using rates up to 180000 frames per second.