Eur. Phys. J. Special Topics 166, 7-10 (2009)
https://doi.org/10.1140/epjst/e2009-00869-y

Vibrations of sessile drops

¹ Laboratoire de Physique de la Matière Condensée, UMR 6622, CNRS – Université de Nice Sophia-Antipolis, Parc Valrose, 06108 Nice Cedex 2, France
² Institut Curie, UMR 168, CNRS – Université Pierre et Marie Curie, 26 rue d'Ulm, 75248 Paris, France

Corresponding author: xavier.noblin@unice.fr

Abstract

This study focuses on the effects of vertical vibrations on sessile drops deposited on hydrophobic substrates. At low amplitudes the contact line remains pinned because of contact angle hysteresis and only drop surface modes are observed. Above a first threshold the contact line starts to move and exhibits a stick-slip behavior that presents some analogies with the solid friction on a mechanical oscillator. At larger amplitudes, non-axisymmetric contour modes show up (modes m=2, 3...). They can be interpreted as a coupling between surface modes and contact line motion. These subharmonic modes are well described within the framework of parametric oscillators. We also discuss here why vibrations can help to measure equilibrium contact angle.