Wetting of crossed fibers: Multiple steady states and symmetry breaking

¹ Department of Mechanical and Aerospace Engineering, Princeton University - Princeton, NJ 08544, USA
² Laboratoire d'Hydrodynamique (LadHyX) and Department of Mechanics, Ecole Polytechnique, CNRS 91128 Palaiseau Cedex, France

Received: 16 January 2014
Accepted: 4 March 2014

Abstract

We investigate the wetting properties of the simplest element of an array of random fibers: two rigid fibers crossing with an inclination angle and in contact with a droplet of a perfectly wetting liquid. We show experimentally that the liquid adopts different morphologies when the inclination angle is increased: a column shape, a mixed morphology state where a drop lies at the end of a column, or a drop centered at the node. An analytical model is provided that predicts the wetting length as well as the presence of a non-symmetric state in the mixed morphology regime. The model also highlights a symmetry breaking at the transition between the column state and the mixed morphology. The possibility to tune the morphology of the liquid could have important implications for drying processes.