Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.21: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

Energy loss of bouncing water drops — •Wolfram Hild, Juergen A. Schaefer, Denis Duft, and Thomas Leisner — TU Ilmenau, Institut für Physik und ZMN, Postfach 100565, 98684 Ilmenau

Water droplets can bounce like an elastic sphere after hitting a super hydrophobic surface. Interestingly, they behave like a spring. The contact time, which corresponds to one period of oscilla-tion of the spring, is independent of impact velocity. However, the velocity of the reflected droplet depends on the impact velocity. Thus, there is a loss of kinetic energy depending on the starting conditions. Energy losses are due to adhesive forces between substrate and droplet and mainly due to excitations of droplet oscillations.

It could be shown that energy losses are due to adhesion at lower velocity. Furthermore, approximately seventy percent of the kinetic energy is transferred to oscillations at higher velocities.