Liquid bridges suspended between horizontal cylinders #

Agnes Bokanyi-Toth, Dmitri Tseluiko, Andrew J Archer, Hemaka Bandulasena

12:10 Tuesday in 4Q08.

Part of the Thin films and contact lines session.

Abstract #

Liquid bridges suspended between two horizontal cylinders are studied using (i) experiments, (ii) direct numerical simulations and (iii) reduced-order model equations. The reduced-order model is based on Onsager’s variational principle, which is equivalent to the minimum energy dissipation principle in Stokesian hydrodynamics. The model equations are implemented in MATLAB, and liquid bridges are investigated both in the presence and absence of gravity. We show both analytically and numerically that the equilibrium contact angle minimises the free energy and the minimum of the Rayleighian function gives the dynamics. The results from the solution of the simplified model are corroborated by direct numerical simulations in COMSOL.

Additionally, we analyse the influence of the electric field resulting from an imposed potential difference between the cylinders on the dynamics of liquid bridges, using a boundary-element method to solve the electric-field equations. We find that electrified bridges move up and develop stable, flatter interfaces.

We also developed an experimental setup and filmed the dynamics of both electrified and non-electrified liquid bridges. Silicone oil droplets were suspended between parallel cylindrical electrodes and observed under high electric fields. We find that the experimental observations are well described by the model equations for a wide range of parameter values.