In 1805, Young was the first who introduced an expression for contact angle in static, but today, the motion of the contact-line formed at the intersection of two immiscible fluids and a solid is still subject to dispute. By means of the new physical concept of line viscosity, the equations of motions and boundary conditions for fluids in contact on a solid surface together with interface and c...

Conditions for thermodynamic equilibrium of liquid drops on solid substrates are presented. It is shown that if surface force (disjoining/conjoining Derjaguin pressure) action in a vicinity of the three-phase contact line is taken into account the condition of thermodynamic equilibrium is duly satisfied. Then the thermodynamic expressions for equilibrium contact angles of drops on solid substra...

in this paper the dynamic of a droplet on a surface with a hole is investigated under gravitational effect by using lattice boltzmann method. incompressible two-phase flow with high density ratio proposed by lee is considered. cahn’s theory is used to observe the wettability of the surface in contact with liquid and gas phases. several parameters such as contact angle, surface tension and gravi...

We report simulation evidence that the structure of the first water layer next to the surface can strongly affect the contact angle of water droplets. Molecular dynamics simulations show that a small uniform strain (± 3%) applied to the lattice constant of a multilayer hydrophilic surface can introduce a marked change in the wetting tendency. In particular, when the lattice constant of a hydrop...

We report the contact line dynamics of sessile water droplets, 1.1-1.6 mm in radius, spread by electrowetting in air. Coplanar electrodes patterned on the substrate allow a true sessile condition with no wire into the droplet. The frequency response of the droplets is studied using 25 VAC ranging from 10 to 205 Hz. The effect of contact angle hysteresis is seen in form of stick-slip motion. A m...

We present a multiscale method to simulate the flow of two immiscible incompressible fluids in contact with solids. The macro model in our method is based on a level set method with sharp interface treatment. The contact line is tracked explicitly and moves according to a slip velocity that depends on the apparent contact angle of the interface with the solid. The relation between apparent cont...

The problem studied is that of a rotationally symmetric liquid bridge between two contacting balls of equal radius, with the same contact angle with both balls, and in the absence of gravity. The bridge surface must be of constant mean curvature, hence a Delaunay surface. If the contact angle is less than π 2 , existence of a rotationally symmetric bridge is shown for a large range of the relev...

We first fabricated the superhydrophobic film with a water contact angle of 178 degrees based on a perpendicular nanopin fractal structure by a bottom-up process. Until now, only materials with an original water contact angle larger than 90 degrees , which is classified as hydrophobicity, could be used to fabricate the superhydrophobic film (>170 degrees ) according to the possible fractal stru...

OBJECTIVE To evaluate the effect that maintaining tracheobronchial sputum at room temperature has on the analysis of ciliary transport and cough, as well as on the contact angle. METHODS Hyaline sputum was collected from 30 individuals without pulmonary diseases, and purulent sputum was collected from patients with bronchiectasis. The samples were analyzed immediately after collection and aga...

In this work, Lennard-Jones liquid and water droplets are simulated adjacent to a solid surface using molecular dynamics. The contact angle is obtained by using direct simulation. The particle-particle particle-mesh method [B. Shi, S. Sinha, and V. K. Dhir, J. Phys. Chem. 124, 204715 (2006)] for long range force correction is used in the simulation. The contact angle is studied as a function of...