scholarly journals Propagation of capillary waves and ejection of small droplets in rapid droplet spreading

2012 ◽  
Vol 697 ◽  
pp. 92-114 ◽  
Author(s):  
H. Ding ◽  
E. Q. Li ◽  
F. H. Zhang ◽  
Y. Sui ◽  
P. D. M. Spelt ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Solid Substrate ◽  
Capillary Waves ◽  
Droplet Spreading ◽  
Complete Wetting ◽  
Droplet Ejection ◽  
Self Similar ◽  
Similar Theory ◽  
First Time ◽  
Good Agreement

AbstractA new regime of droplet ejection following the slow deposition of drops onto a near-complete wetting solid substrate is identified in experiments and direct numerical simulations; a coalescence cascade subsequent to pinch-off is also observed for the first time. Results of numerical simulations indicate that the propagation of capillary waves that lead to pinch-off is closely related to the self-similar behaviour observed in the inviscid recoil of droplets, and that motions of the crests and troughs of capillary waves along the interface do not depend on the wettability and surface tension (or Ohnesorge number). The simulations also show that a self-similar theory for universal pinch-off can be used for the time evolution of the pinching neck. However, although good agreement is also found with the double-cone shape of the pinching neck for droplet ejection in drop deposition on a pool of the same liquid, substantial deviations are observed in such a comparison for droplet ejection in rapid drop spreading (including the newly identified regime). This deviation is shown to result from interference by the solid substrate, a rapid downwards acceleration of the top of the drop surface and the rapid spreading process. The experiments also confirm non-monotonic spreading behaviour observed previously only in numerical simulations, and suggest substantial inertial effects on the relation between an apparent contact angle and the dimensionless contact-line speed.

scholarly journals Numerical Simulations of the Impact and Spreading of a Particulate Drop on a Solid Substrate

2012 ◽  
Vol 2012 ◽  
pp. 1-10
Author(s):  
Hyun Jun Jeong ◽  
Wook Ryol Hwang ◽  
Chongyoup Kim
Keyword(s):  
Numerical Simulations ◽  
Solid Surface ◽  
Reynolds Numbers ◽  
Suspended Particles ◽  
Solid Substrate ◽  
Oscillatory Behavior ◽  
Navier Stokes ◽  
Droplet Spreading ◽  
Navier Stokes Equation ◽  
The Impact

We present two-dimensional numerical simulations of the impact and spreading of a droplet containing a number of small particles on a flat solid surface, just after hitting the solid surface, to understand particle effects on spreading dynamics of a particle-laden droplet for the application to the industrial inkjet printing process. The Navier-Stokes equation is solved by a finite-element-based computational scheme that employs the level-set method for the accurate interface description between the drop fluid and air and a fictitious domain method for suspended particles to account for full hydrodynamic interaction. Focusing on the particle effect on droplet spreading and recoil behaviors, we report that suspended particles suppress the droplet oscillation and deformation, by investigating the drop deformations for various Reynolds numbers. This suppressed oscillatory behavior of the particulate droplet has been interpreted with the enhanced energy dissipation due to the presence of particles.

Sharp acceleration of a macroscopic contact line induced by a particle

2017 ◽  
Vol 830 ◽  
Author(s):  
Lizhong Mu ◽  
Daichi Kondo ◽  
Motochika Inoue ◽  
Toshihiro Kaneko ◽  
Harunori N. Yoshikawa ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Surface Area ◽  
Contact Line ◽  
Late Stage ◽  
Silicone Oil ◽  
Particle Interaction ◽  
Solid Substrate ◽  
Complete Wetting ◽  
Short Time ◽  
Good Agreement

Wetting of a planar solid substrate is investigated in the presence of a macroscopic particle in the complete wetting regime. A drop of silicone oil spreads on the substrate and its macroscopic edge is incident on the particle at the late stage of spreading. The drop–particle interaction is observed in detail by shadowgraph and interferometry. Although the spreading drop edge is pinned by the particle for a short time, a sharp acceleration occurs when the liquid starts wetting the extra surface area offered by the particle and forming a meniscus. This process yields a net gain in spreading speed. A theoretical model based on the classical wetting dynamics dictated by Cox’s law is developed. It predicts that the capillary energy of the meniscus gives rise to a rapid motion of the liquid edge, showing good agreement with the dynamics observed in the experiments.

Ratchet mechanism of drops climbing a vibrated oblique plate

2017 ◽  
Vol 835 ◽  
Author(s):  
Hang Ding ◽  
Xi Zhu ◽  
Peng Gao ◽  
Xi-Yun Lu
Keyword(s):  
Contact Angle ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Contact Angle Hysteresis ◽  
Three Dimensional ◽  
Direct Numerical Simulations ◽  
Ratchet Mechanism ◽  
Wetted Area ◽  
First Time ◽  
Good Agreement

In this paper, we investigate the ratchet mechanism of drops climbing a vibrated oblique plate based on three-dimensional direct numerical simulations, which for the first time reproduce the existing experiment (Brunet et al., Phys. Rev. Lett., vol. 99, 2007, 144501). With the help of numerical simulations, we identify an interesting and important wetting behaviour of the climbing drop; that is, the breaking of symmetry due to the inclination of the plate with respect to the acceleration leads to a hysteresis of the wetted area in one period of harmonic vibration. In particular, the average wetted area in the downhill stage is larger than that in the uphill stage, which is found to be responsible for the uphill net motion of the drop. A new hydrodynamic model is proposed to interpret the ratchet mechanism, taking account of the effects of the acceleration and contact angle hysteresis. The predictions of the theoretical analysis are in good agreement with the numerical results.

A study of plasma expansion phenomena in laboratory generated plasma wakes: preliminary results

1985 ◽  
Vol 33 (1) ◽  
pp. 71-82 ◽  
Author(s):  
K. H. Wright ◽  
N. H. Stone ◽  
U. Samir
Keyword(s):  
Early Time ◽  
Detailed Comparison ◽  
Plasma Expansion ◽  
Near Wake ◽  
Space Potential ◽  
Self Similar ◽  
The Creation ◽  
Similar Theory ◽  
Chamber Size ◽  
Good Agreement

The plasma expansion into the wake of a large rectangular plate immersed in a single-ion, collisionless, streaming plasma has been investigated in the laboratory. Several characteristics of the process involved in ‘plasma expansion into vacuum’ that have been predicted theoretically were observed, including the creation and motion of a rarefaction wave disturbance; the creation and motion of an expansion front; and the acceleration of ions into the wake at speeds above the ion-acoustic speed. The expansion was limited to early times; i.e. a few ion plasma periods, by the combination of plasma drift speed and vacuum chamber size. This prevented detailed comparison with self-similar theory, but results are in good agreement with numerical simulations and other laboratory experiments for the early time expansion. The conclusion is that the plasma expansion process is the dominant wake filling mechanism in the near wake of a body, whose potential is approximately the plasma space potential.

scholarly journals Numerical simulations of dense clouds on steep slopes: application to powder-snow avalanches

2004 ◽  
Vol 38 ◽  
pp. 379-383 ◽  
Author(s):  
Jocelyn Étienne ◽  
Pierre Saramito ◽  
Emil J. Hopfinger
Keyword(s):  
Numerical Simulations ◽  
Local Density ◽  
Direct Numerical Simulations ◽  
Two Dimensional ◽  
Snow Avalanches ◽  
Velocity Variations ◽  
Steep Slopes ◽  
First Time ◽  
Spatial Growth Rate ◽  
Good Agreement

AbstractIn this paper, two-dimensional direct numerical simulations (DNS) of dense clouds moving down steep slopes are presented for the first time. The results obtained are in good agreement with the overall characteristics, i.e. the spatial growth rate and velocity variations, of clouds studied in the laboratory. In addition to the overall flow structure, DNS provide local density and velocity variations inside the cloud, not easily accessible in experiments. The validity of two-dimensional simulations as a first approach is confirmed by the dynamics of the flow and by comparison with experimental results. The interest of the results for powder-snow avalanches is discussed; it is concluded that two-dimensionality is acceptable and that large density differences need to be taken into account in future simulations.

Vorticity generated by pure capillary waves

2002 ◽  
Vol 459 ◽  
pp. 277-288 ◽  
Author(s):  
SHAHRDAD G. SAJJADI
Keyword(s):  
Numerical Simulations ◽  
Gravity Wave ◽  
Gravity Waves ◽  
Velocity Fields ◽  
Capillary Waves ◽  
Second Order ◽  
Experimental Measurements ◽  
Vorticity Field ◽  
Stokes Layer ◽  
Good Agreement

Capillary waves, like other surface waves on water, generate a rectified, or time-averaged, vorticity field extending beyond the oscillatory (Stokes) layer at the surface. This vorticity field ω is particularly interesting in relation to the parasitic capillary waves found on the forward slopes of steep gravity waves. Longuet-Higgins (1992) suggested that the rectified vorticity from the parasitic capillaries might contribute significantly to the vorticity observed beneath the crest of the gravity wave. The basic calculations by Longuet-Higgins (1992) were only of the horizontally averaged values of ω. Here we extend his theory by calculating, for pure capillary waves, the space variation of ω, to second order in the steepness of the capillary waves. Thus, the vorticity, and hence velocity, fields are calculated in the oscillatory Stokes layer and just beyond it, to the second order. Good agreement is found both with numerical simulations and with experimental measurements.

scholarly journals 3D simulations of internal gravity waves in solar-like stars

2013 ◽  
Vol 9 (S301) ◽  
pp. 375-376
Author(s):  
Lucie Alvan ◽  
Allan Sacha Brun ◽  
Stéphane Mathis
Keyword(s):  
Numerical Simulations ◽  
Gravity Waves ◽  
Rotation Rate ◽  
Spherical Harmonic ◽  
Internal Gravity Waves ◽  
3D Simulations ◽  
Frequency Splitting ◽  
Theoretical Predictions ◽  
First Time ◽  
Good Agreement

AbstractWe perform numerical simulations of the whole Sun using the 3D anelastic spherical harmonic (ASH) code. In such models, the radiative and convective zones are non-linearly coupled and in the radiative interior a wave-like pattern is observed. For the first time, we are thus able to model in 3D the excitation and propagation of internal gravity waves (IGWs) in a solar-like star's radiative zone. We compare the properties of our waves to theoretical predictions and results of oscillation calculations. The obtained good agreement allows us to validate the consistency of our approach and to study the characteristics of IGWs. We find that a wave's spectrum is excited up to radial order n=58. This spectrum evolves with depth and time; we show that the lifetime of the highest-frequency modes must be greater than 550 days. We also test the sensitivity of waves to rotation and are able to retrieve the rotation rate to within 5% error by measuring the frequency splitting.

Multicanonical Molecular Dynamics Simulation Study of the Liquid-Solid and Solid-Solid Transitions in Lennard-Jones Clusters

2011 ◽  
Author(s):  
Toshihiro Kaneko ◽  
Kenji Yasuoka ◽  
Ayori Mitsutake ◽  
Xiao Cheng Zeng
Keyword(s):  
Molecular Dynamics ◽  
Heat Capacity ◽  
Transition Temperature ◽  
Peak Position ◽  
Temperature Curve ◽  
Dynamics Simulation ◽  
Lennard Jones ◽  
Dynamics Simulations ◽  
First Time ◽  
Good Agreement

Multicanonical molecular dynamics simulations are applied, for the first time, to study the liquid-solid and solid-solid transitions in Lennard-Jones (LJ) clusters. The transition temperatures are estimated based on the peak position in the heat capacity versus temperature curve. For LJ31, LJ58 and LJ98, our results on the solid-solid transition temperature are in good agreement with previous ones. For LJ309, the predicted liquid-solid transition temperature is also in agreement with previous result.

scholarly journals Sarocladium and Lecanicillium Associated with Maize Seeds and Their Potential to Form Selected Secondary Metabolites

Biomolecules ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 98
Author(s):  
Lidia Błaszczyk ◽  
Agnieszka Waśkiewicz ◽  
Karolina Gromadzka ◽  
Katarzyna Mikołajczak ◽  
Jerzy Chełkowski
Keyword(s):  
Large Subunit ◽  
Solid Substrate ◽  
Rrna Gene ◽  
Decenoic Acid ◽  
Bioactive Substances ◽  
Lecanicillium Lecanii ◽  
Maize Seeds ◽  
Internally Transcribed Spacer ◽  
First Time

The occurrence and diversity of Lecanicillium and Sarocladium in maize seeds and their role in this cereal are poorly understood. Therefore, the present study aimed to investigate Sarocladium and Lecanicillium communities found in endosphere of maize seeds collected from fields in Poland and their potential to form selected bioactive substances. The sequencing of the internally transcribed spacer regions 1 (ITS 1) and 2 (ITS2) and the large-subunit (LSU, 28S) of the rRNA gene cluster resulted in the identification of 17 Sarocladium zeae strains, three Sarocladium strictum and five Lecanicillium lecanii isolates. The assay on solid substrate showed that S. zeae and S. strictum can synthesize bassianolide, vertilecanin A, vertilecanin A methyl ester, 2-decenedioic acid and 10-hydroxy-8-decenoic acid. This is also the first study revealing the ability of these two species to produce beauvericin and enniatin B1, respectively. Moreover, for the first time in the present investigation, pyrrocidine A and/or B have been annotated as metabolites of S. strictum and L. lecanii. The production of toxic, insecticidal and antibacterial compounds in cultures of S. strictum, S. zeae and L. lecanii suggests the requirement to revise the approach to study the biological role of fungi inhabiting maize seeds.

Darstellung, Schwingungsspektren und Normalkoordinatenanalyse von Chloro-Bromo-Rhodaten(III) / Preparation, Vibration Spectra and Normal Coordinate Analysis of Chloro-Bromo-Rhodates(III)

1989 ◽  
Vol 44 (10) ◽  
pp. 1221-1227 ◽  
Author(s):  
W. Preetz ◽  
W. Kuhr
Keyword(s):  
Exchange Chromatography ◽  
Trans Isomers ◽  
Normal Coordinate ◽  
Valence Force ◽  
Trans Influence ◽  
Diethylaminoethyl Cellulose ◽  
Point Groups ◽  
First Time ◽  
Ir And Raman ◽  
Good Agreement

The mixed chloro-bromo-rhodates(III) [RhClnBr6-n]3-, n = 1-5, have been separated for the first time by ion exchange chromatography on diethylaminoethyl-cellulose. Due to the stronger trans-effect of Br, as compared with Cl, on treatment of [RhBr6]3- with conc. HCl nearly pure cis/fac-isomers for n = 2, 3, 4 are formed. The reaction of [RhCl6]3- with conc. HBr yields mixtures of the cis/trans-isomers for n = 2, 4, which cannot be separated, but mer-[RhCl3Br3]3 is formed stereospecifically. The IR and Raman spectra of all isolated mixed ligand complexes are completely assigned according to point groups Oh, D3d, C4v, C3v and C2v, supported by normal coordinate analyses based on a general valence force field. The good agreement of calculated and observed frequencies confirms the assignments. Due to the stronger trans-influence of Br as compared to Cl, in all asymmetric Cl—Rh—Br axes the Rh—Br bonds are strengthened and the Rh—Cl bonds are weakened, indicated by valence force constants for Rh—Br approximately 14% higher, for Rh—Cl 10% lower, as compared with the values calculated for symmetric Br—Rh—Br and Cl—Rh—Cl axes, respectively.

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