Instabilities in a drop-strip system: a simplified model

Abstract

We study the deformation of an elastic strip by a liquid drop. At small enough scales, capillarity is the dominant fluid effect and surface tension forces may be sufficient to fold the beam, resulting in the wrapping of the drop by the beam. However, wrapping of the drop can be inhibited by the weight of the beam, which creates an energy barrier. The barrier can be overcome by input of kinetic energy in the form of impact of the drop. We introduce a semi-analytical model to study equilibria and their stability in three drop-beam systems: evaporation of a drop wetting and bending an elastic beam; impact of a drop on an elastic beam; lifting of a heavy elastic beam by a drop and we show the model reproduces experimental data. In relevant cases, we use the concept of suddenly applied load to discuss dynamic instabilities.