General Methodology for Evaluating the Adhesion Force of Drops and Bubbles on Solid Surfaces

Abstract

The shortcomings of the current formulation for calculating the adhesion force for drops and bubbles with noncircular contact lines are discussed. A general formulation to evaluate the adhesion force due to surface forces is presented. Also, a novel methodology, that is, IBAFA, image based adhesion force analysis, was developed to allow implementation of the general formulation. IBAFA is based on the use of multiple profile images of a drop. The images are analyzed (1) to accurately reconstruct the contact line shape, which is analytically represented by a Fourier cosine series, and (2) to measure contact angles at multiple locations along the contact line and determine the contact angle distribution based on a linear piecewise interpolation routine. The contact line shape reconstruction procedure was validated with both actual experiments and simulated experiments. The procedure for the evaluation of the adhesion force was tested using simulated experiments with synthetic drops of known shapes. A comparison with current methods showed that simplifying assumptions (e.g., elliptical contact line or linear contact angle distribution) used in these methods result in errors up to 76% in the estimated adhesion force. However, the drop adhesion force evaluated using IBAFA results in small errors on the order of 1%.

A semi-analytical model for droplet dynamics on the GDL surface of a PEFC electrode

“…As Antonini et al showed in their work [17], for hydrophobic surfaces with static contact angle greater than 90…”

“…This expression is integrated numerically to obtain the approximated value of the adhesion force at every deformation state [17]. As Antonini et al showed in their work [17], for hydrophobic surfaces with static contact angle greater than 90…”

The impact and freezing processes of a water droplet on a cold surface with different inclined angles

“…However, once a water droplet is placed on an inclined surface, gravity is applied to such a resting droplet. Thus, the contact angle distribution along the contact line must distort in order to resist the droplet motion [19]. The differences in the geometries of the sessile water droplets result in the variations of the shape of the ice bead eventually.…”

VOF simulations of the contact angle dynamics during the drop spreading: Standard models and a new wetting force model

“…The idea behind the derivation of the Wetting Force Model comes from the work of Antonini et al [75]. The authors investigated experimentally the adhesion force of a droplet sliding down an inclined surface and they derived a methodology for the prediction of this "adhesion" force.…”