We show that in general, the specification of a contact angle condition at the contact line in inviscid fluid motions is incompatible with the classical field equations and boundary conditions generally applicable to them. The limited conditions under which such a specification is permissible are derived; however, these include cases where the static meniscus is not flat. In view of this situat...

Capillary dependent systems are highly influenced by surface fouling and may degrade as material surface properties change. In anticipation of a spacecraft microgravity fluids management system exposed to highly variable wetting conditions, the impact of urine wastewater fouling on capillary contact angle was examined. The results indicate that, in general, surface fouling can decrease the cont...

We present a model which explains several experimental observations relating contact angle hysteresis with surface roughness. The model is based on the balance between released energy and dissipation, and it describes the stick–slip behavior of drops on a rough surface using ideas similar to those employed in dry friction, elasto– plasticity and fracture mechanics. The main results of our analy...

Adhesive and marine biofouling release properties of coatings containing surface-oriented perfluoroalkyl groups were investigated. These coatings were prepared by cross-linking a copolymer of 1H,1H,2H,2H-heptadecafluorodecyl acrylate and acrylic acid with a copolymer of poly(2-isopropenyl-2-oxazoline) and methyl methacrylate at different molar ratios. The relationships between contact angle, co...

We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ϕS. It is shown that the receding regime is determined by a longitudinal sliding motion of the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e., is practically the same in the longitu...

A novel method to calculate the solid-liquid contact angle is introduced in this study. Using the 3D configuration of a liquid droplet on a solid surface, this method calculates the contact angle along the contact line and provides an angular distribution. Although this method uses the 3D configuration of liquid droplets, it does not require the calculation of the 3D density profile to identify...

This work focuses on three-dimensional simulation of the dynamics droplets with contact-angle hysteresis. In order to consistently model contact line, a combination linear molecular kinetic theory and hydrodynamic is implemented in present numerical method. Without presetting line and/or angle, such simulations are generally prone irregularities at which mainly due imposition pinning unpinning ...

Image-analyzing interferometry is used to measure the apparent contact angle and the curvature of a drop and a meniscus during condensation and evaporation processes in a constrained vapor bubble (CVB) cell. The apparent contact angle is found to be a function of the interfacial mass flux. The interfacial velocity for the drop during condensation and evaporation is a function of the apparent co...

In this paper, we derive a modified Cassie’s equation for wetting on chemically patterned surfaces from a homogenization approach. The derivation reveals that effective contact angle is a local average of the static contact angle along the contact line which describes all possible equilibrium states including the local minimum of the free energy of the system. The usual Cassie’s state which cor...