In the present work experimental, numerical, and theoretical investigations of a normal drop impact onto liquid film finite thickness are presented. The dynamics on surfaces, shape cavity, formation propagation capillary wave in crater, residual rigid wall determined analyzed. crater within uprising sheet formed upon observed using high-speed video system. effects various influencing parameters such as velocity, physical properties liquids, including viscosity surface tension, time evolution...

This paper presents results of an experimental investigation a single drop impact onto dry, partially wettable substrate and its numerical simulation. Particularly, the spreading diameter dynamic contact angle are measured at different time instants after impact. Two surfaces, wax (low wettability) glass (high wettability), used to study effect surface wettability (static angle) on dynamics. It is shown that existing empirical models for (e.g., Hoffman–Voinov–Tanner law) do not predict well...

The normal impact of a liquid drop on dry solid surface is studied experimentally and theoretically. In this paper strictly theoretical model introduced, which predicts the evolution diameter. spreading receding phases are described by motion rim appearing at edge film (lamella) due to surface–tension forces. mass momentum equations considered, taking into account effects inertial, viscous forces, wettability. Also, simplified approximations for maximum diameter velocity merging in phase...

This study is devoted to a theoretical description of an unsteady laminar viscous flow in spreading film Newtonian fluid. Such generated by normal drop impact onto dry substrate with high Weber and Reynolds numbers. An analytical self-similar solution for the obtained which satisfies full Navier–Stokes equations. The characteristic thickness boundary layer developed near wall uniformly increases as square root time. expression used estimation residual formed maximum diameter. predictions...

The impact of a drop onto liquid film with relatively high velocity, leading to the formation crown-like ejection, is studied theoretically. motion kinematic discontinuity in on wall due impact, upward jet at this and its elevation are analysed. Four main regions considered: perturbed inside crown, unperturbed outside forming free rim bounding jet. theory Yarin & Weiss (1995) for propagation generalized here case arbitrary velocity vectors inner outer films wall. Next, mass, momentum...

This paper reports on experimental and theoretical investigations of the impact a droplet onto spherical target. Spatial temporal variation film thickness target surface is measured. Three distinct phases dynamics are clearly visible from results, namely initial drop deformation phase, inertia dominated viscosity phase. Experiments also conducted to study effect Reynolds number target-to-drop size ratio flow It observed that for given ratio, nondimensional collapses single curve in first...

This study is devoted to the analysis of inertia dominated axisymmetric drop collisions with a dry substrate or another liquid drop. All previous theoretical and semiempirical models are based on assumption that flow in lamella its thickness determined by impact conditions, mainly Reynolds Weber numbers. In this existing experimental data compared new numerical simulations for shape generated at early times various conditions. The results show if numbers high enough, evolution almost does...

In this paper, normal spray impact onto a rigid wall, leading to the formation of secondary spray, is considered. The mechanism splash explained by bending instability rim bounding free liquid sheet. linear stability analysis performed in framework long-wave, quasi-one-dimensional approach. caused moment forces associated with inertia entering rim. Next, two components drop velocity and their diameter, as well various flux density vectors (number, volume, mass fluxes) tensors (momentum...

Experiments were conducted to study peculiarities of drop impact onto electrospun polymer nanofiber mats. The cross-sectional diameters the order several hundred nanometers, pore sizes in mats about micrometers, and mat thicknesses 200 microm. Polyacrylonitrile (PAN), a which is partially wettable by water, was used electrospin experiments revealed that nanotextured surfaces produce spreading similar on impermeable surfaces. However, at end stage, contact line pinned receding prevented. At...

This experimental study is focused on the mechanisms of thermal atomisation a drop impacting onto hot substrate. phenomenon characterised by wetting and dewetting substrate, caused not rim dynamics, but induced effects. These effects lead to lamella evaporation, levitation disintegration, generation vertical spray fine droplets consequently, breakup. A typical contact time before complete detachment theoretically estimated. estimation agrees very well with experiments. It shown that Weber...

This paper is devoted to an experimental and theoretical investigation of the crater formed by impact a single drop onto semi-infinite target same liquid. The shape at various time instances after has been observed using high-speed video system then accurately characterized. A model for expansion developed, which able predict temporal variation depth sufficiently high Weber, Froude, Reynolds numbers. flow around approximated irrotational velocity field past moving expanding sphere. equations...

The Leidenfrost effect is a technically and industrially important phenomenon that severely restricts heat removal from high-heat-flux surfaces. A simple remedy to the provided by polymer nanofiber mats created deposited electrospinning on stainless steel influence of hydrodynamics cooling efficiency single drop impact onto hot surfaces has been investigated experimentally. evolution drops recorded high-speed complimentary metal-oxide semiconductor camera, whereas temperature was measured...

This study is devoted to the experimental and theoretical investigation of aerodynamic drop breakup phenomena. We show that phenomena impact onto a rigid wall, binary collisions, deformation are similar if correct scaling applied. Then we use observations deforming estimate evolution film thickness bag, value determines size fine child drops produced by bag breakup. prediction thickness, based on kinematics, validated for initial stage direct measurements at latest data obtained from...

In this experimental and theoretical study, the impact of non-spherical spherical ice particles onto a solid surface is investigated. The velocity was varied between 1 74 m s −1 . size ranged from 30 μm to 3.5 mm. target consisted tiltable aluminium surface. angles were set 30° 90° (normal impact). process recorded by high-speed video system. Based on observations, four different fragmentation modes, characterized levels particle damage, defined. Fragmentation models for description...

The impact of water drops onto a solid surface at subfreezing temperatures has been experimentally studied. Drop nucleation observed using high-speed video system. statistics allows the estimation average number sites per unit area wetted part substrate. We have discovered that rate in impacting drop is not constant. significant increase small times after $t<50$ ms can be explained by generation nanobubbles early impact. These bubbles serve as additional and enhance rate.