We first study the impact of a liquid drop low viscosity on super-hydrophobic surface. Denoting size and speed as are density surface tension). This law is also observed to hold partially wettable surfaces, provided that liquids (such water) used. The interpreted resulting from effective acceleration experienced by during its impact. Viscous drops analysed, allowing us propose criterion for predicting if spreading limited capillarity, or viscosity.

A Leidenfrost drop forms when a volatile liquid is brought in contact with very hot solid. Then, vapor film comes between the solid and drop, giving to latter appearance of pearl. After brief description shape we show that its size cannot exceed certain value. describe characteristics layer on which it floats. We how related size, both vary time, as evaporation takes place. finally deduce scaling laws for lifetime these drops.

Abstract It has been recently shown that the presence of macrotextures on superhydrophobic materials can markedly modify dynamics water impacting them, and in particular significantly reduce contact time bouncing drops, compared with what is observed a flat surface. This finding constitutes significant step maximization repellency, since it enables to minimize even further between solid liquid. also opens new axis research design super-structures induce specific functions such as...

We describe the first steps of spreading a liquid droplet brought in contact with solid that it wets completely. Usually, is assumed dynamics results from balance between forces and viscosity. But before this classical stage, inertia resists to motion, which leads very different dynamic law. study experimentally nature law, compare our recent theoretical predictions, determine duration inertial regime.

We consider the critical Weber number ( c ≡ ρ V 2 0 D /σ) at which transition from dripping to jetting occurs when a Newtonian liquid of density and surface tension σ is injected with velocity through tube diameter downward into stagnant air, under gravity g . extend Taylor's (1959) model for recession speed free edge, obtain in inviscid limit an exact solution includes inertia effects. This provides criterion shown occur formula here where Bo o are Bond numbers ≡[ρg /(2σ)] 1/2 ),...

A drop of low viscosity hitting a solid may bounce, provided that the material is highly hydrophobic. As model such situation, we consider here case very hot solid. Then, as discovered by Leidenfrost, thin layer vapour sustains drop, preventing any contact with substrate. On solid, rebounds, and discuss elasticity shock. Two different cases are described: at large velocity, weaker impact elasticity; small quasi-elastic regime found. The boundary between two domains set Weber number, which...

It has been shown that a water drop can bounce persistently, when thrown on super-hydrophobic substrate. We present here scaling arguments which allow us to predict the maximal deformation and contact time of drop. This approach is completed by model describing flow inside drop, original experimental data.

We study the collapse of a transient cavity air in water created by impact solid body. Experimentally, we characterize dynamics from its creation ( t = 0) until it collapses τ) limit where inertia dominates viscous and capillary effects. Theoretically, find this regime an approximate analytical solution which describes time evolution shape cavity. This theoretical predicts existence two different types cavities that also observe experimentally.

Superhydrophobic surfaces generate very high contact angles as a result of their microstructure. The impact water drop on such surface shows unusual features, total rebound at low speed. We report experimental and numerical investigations the approximately spherical drops. axisymmetric free problem, governed by Navier–Stokes equations, is solved numerically with front-tracking marker-chain method square grid. Experimental observations moderate velocities capillary wavelength much less than...

We study the capillary rise of wetting liquids in corners different geometries and show that meniscus rises without limit following universal law: h(t)/a ≈ (γt/ηa)1/3, where γ η stand for surface tension viscosity liquid while is length, based on density ρ gravity g. This law sense it does not depend geometry corner.

Superhydrophobicity is mainly remarkable for the special dynamical behaviours it generates: low adhesion, giant hydrodynamic slip, frictionless motion, rebounds after impacts. Here we discuss most of these properties. We first recall how contact angle hysteresis can be minimized in this state. Then, show that a water drop follows Galilean law free fall on an incline, before reaching stationary state, which associated friction. Finally, property repellency (that is, impact) presented....

We discuss the special laws of friction observed as a drop glides on liquid-infused material.

Drop impacts are difficult to characterize due their transient, non-stationary nature.

Texturing a flat superhydrophobic substrate with point-like macrotextures of the same repellency makes impacting water droplets take off as rings, which leads to shorter bouncing times than on substrate.

A round liquid jet with density ρ, surface tension σ and diameter D 0 impacting a solid circular at normal incidence velocity U takes the form of radially expanding sheet whose thickness decreases distance from impact point. When develops in still environment ρ = αρ, it destabilizes, provided Weber number We 2 0/σ is larger than about 40α −1/2 , as result shear instability surrounding medium, sinuous, flag-like motion. show how properties set both radial extent drop formation process its...

This paper presents the first direct experimental measurements of growth rate Darrieus-Landau instability on a planar laminar premixed flame front. Prior to measurements, intrinsically unstable is maintained stable by novel technique based response an acoustic parametric forcing. The rates instability, measured when forcing removed, are in agreement with theoretically predicted values.

An evaporating drop placed on a ratchet self-propels, as discovered by Linke et al. in 2006. Sublimating platelets do the same, and we discuss here possible viscous mechanism for these motions. We report that flow of vapor below levitating material is rectified asymmetric teeth ratchet, direction descending slopes along each tooth. As consequence, resulting stress can entrain same direction, self-propelling force.

We discuss how a solid textured with well-defined micropillars entrains film when extracted out of bath wetting liquid. At low withdrawal velocity V , it is shown experimentally that the exactly fills gap between pillars; its thickness h d independent and corresponds to pillar height p . larger velocity, slowly increases tends towards Landau–Levich–Derjaguin (LLD) LLD observed on flat solid. model entrainment by adapting theory double layer consisting liquid trapped inside texture covered...