Dresden 2011 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 13: Fluid Dynamics and Turbulence I

DY 13.3: Talk

Tuesday, March 15, 2011, 11:00–11:15, ZEU 118

Generation and quantitative analysis of thickness modulations on micron sized liquid sheets — •Paul Steffen and Stephan Herminghaus — MPI for Dynamics and Self-Organization, Göttingen

The destabilization of liquids and liquid sheets by surface deformations is a major mechanism for the production of micron sized droplets. We investigate periodic thickness modulations on moving liquid sheets of different viscosities, at thicknesses below 100 microns and surrounded by air. The excitation of the thickness modulations is obtained by piezo driven velocity oscillations at the outlet of an annular nozzle. The analysis of the modulations is performed by direct observation of the liquid/air-interface and by employing the diffraction effects of the sheet on a transmitted laser beam. Quantitative measurements of the amplitude and wave length of the thickness modulations as a function of the frequency and strength of the excitation are presented. For thickness modulation depths up to 30% of the sheet thickness we mainly excite thickness oscillations and interference between the resulting capillary waves. The modulation wave length is as expected. For larger amplitudes up to the break up of the sheet we observed lateral structures as well. Their interpretation is still under investigation.