Oscillation characteristics of low Weber number impinging micro-droplets

Das, Subrat; Mohammed, Mazher Iqbal; Gibson, Ian; Weerasiri, Lanka Dinushke; McDonnell, Amarin G.; Xiang, Junting; Yeo, Leslie

doi:10.1007/s00162-019-00489-9

Cited by 8 publications

(3 citation statements)

References 50 publications

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“…The presence of quasi-elastic and dissipative mechanisms in the metal melt in the AMF is evident from the appearance of oscillations during regime changes and their subsequent damping. Similar damped oscillations have been observed in the melt meniscus in the AMF by P. Buliński, J. Smolka, S. Golack, et al in [49], and in the form of droplets by S. Das, M. Mohammed, I. Gibson, et al in [50]. The mathematical illustration of the accelerative and decelerative action of the Lorentz force, based on melt velocity, is provided by A.I.…”

Section: The Magnitude Of the Velocity Oscillations Increases With De...supporting

confidence: 62%

Rupture of Thin Film Covering the Liquid Metal Stirred by Alternating Magnetic Field. Numerical Simulation

Nikulin,

Demin,

Nukulina

2023

Preprint

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The present work deals with the technological process of induction melting of heat-resistant nickel alloys and, in particular, with the problem of formation and stability of oxide film on the surface of the melt. Our mathematical model describes the heat and mass transfer in the metal melt subjected to the influence of an alternating magnetic field, and the elastic stress states of the film on its surface. The governing equations of the problem are given and non-dimensional parameters are discussed. It is shown how the influence of the magnetic field strength on the flow of the metal melt changes at different frequencies. The states of the surface film are studied theoretically using numerical simulation. It is shown that the variation of the field strength at different frequencies leads to decaying oscillations in the velocity field. The causes of these oscillations are discussed in detail. The stress and destruction of thin films by melt motion are considered. The mechanisms responsible for the primary destruction of the initial film and its fragments are revealed. The rupture of quasi-stable films at different frequencies is studied. It is shown that the result of the influence on the film state with the increase of the magnetic field strength depends on the field frequency. The frequency range was found in which the surface film is strong enough to prevent the intensification of the melt flow with the increase of the magnetic field strength, this effect provides the stability of the film.

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Section: The Magnitude Of the Velocity Oscillations Increases With De...supporting

confidence: 62%

Rupture of Thin Film Covering the Liquid Metal Stirred by Alternating Magnetic Field. Numerical Simulation

Nikulin,

Demin,

Nukulina

2023

Preprint

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“…In the first cycle of oscillation, droplets exhibit a peculiar stick−slip behavior, 46,52,53 where the contact line accelerates sharply while retracting, followed by a quick increase in the contact angle. The stick−slip behavior was observed in most of Data points in the positive velocity region are for the advancing apparent contact angle when droplets are spreading.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Effect of Surface Roughness on Hydrodynamic Characteristics of an Impinging Droplet

Singh

Hodgson

Sen³

et al. 2021

Langmuir

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The influence of surface roughness and impact energy on the hydrodynamic behavior of water droplets impinging upon dry and rigid surfaces of known roughness has been investigated experimentally. The influence of these two parameters on the droplet maximum spreading diameter, slip length during droplet recoil, dynamic contact angle, contact angle hysteresis, and apparent contact angle of droplets at rest has been determined. Based on the quantitative assessment, a correlation for the maximum spreading diameter in terms of the nondimensional parameter (We/Oh) and surface roughness ratio (R a/d o) was derived. We propose to use surface roughness “R a” rather than using the contact angle for correlation as contact angles cannot be known a priori, whereas surface roughness can be determined beforehand. The wetting state of a droplet depends on the combined influence of droplet impact energy and surface roughness. While increasing impact energy increases the spreading, higher surface roughness resists the droplet from spreading. Low impact energy and a smoother surface tend toward the Cassie–Baxter wetting state, whereas high impact energy and rough surfaces propel the droplet toward the Wenzel state of wetting.

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“…In order to verify the theoretical prediction, numerical calculations are systematically carried out based on the powerful software 'Fluent', which has been used to study processes such as droplet impacting and droplet merging [63][64][65][66][67][68][69][70].…”

Section: Verification Of Numerical Calculationsmentioning

confidence: 99%

One-level microstructure-arrayed hydrophobic surface with low surface adhesion and strong anti-wetting function

Huang

Yao

Peng

et al. 2021

J. Phys.: Condens. Matter

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To achieve both a low surface adhesion function and a high anti-wetting function, it is generally necessary to introduce multi-level micro-nano-structures on a surface. However, this will bring the difficulty of preparation technology, and the functions will fail due to the fact that the nanostructures can easily be damaged. In this research, the surface adhesion and anti-wetting properties of several typically one-level microstructure-arrayed hydrophobic surfaces are analyzed with the dynamics theory, including a square pillar-arrayed three-dimensional microstructure, a conical table-arrayed microstructure, and square frustum-arrayed microstructure. It is found that the anti-adhesion performance and anti-wetting property cannot achieve the best performance simultaneously on the one-level microstructure arrayed surfaces. Either the critical pressure of anti-wetting is finite when the surface adhesion is the lowest, or both the anti-adhesion and anti-wetting capacities are finite. However, an interesting phenomenon is found in that the square frustum-arrayed surface can not only achieve an almost infinite anti-wetting capacity when the distance between neighboring microstructures vanishes, but also reach near-zero adhesion when the square frustum reduces to a square pyramid. All the theoretical predictions are further verified by precise numerical simulations. The results of this paper should be helpful for the design of surfaces with low surface adhesion and strong anti-wetting functions in practical engineering.

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Oscillation characteristics of low Weber number impinging micro-droplets

Cited by 8 publications

References 50 publications

Rupture of Thin Film Covering the Liquid Metal Stirred by Alternating Magnetic Field. Numerical Simulation

Rupture of Thin Film Covering the Liquid Metal Stirred by Alternating Magnetic Field. Numerical Simulation

Effect of Surface Roughness on Hydrodynamic Characteristics of an Impinging Droplet

One-level microstructure-arrayed hydrophobic surface with low surface adhesion and strong anti-wetting function

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