scholarly journals Flowering in bursting bubbles with viscoelastic interfaces

2021 ◽  
Vol 118 (30) ◽  
pp. e2105058118
Author(s):  
Daniele Tammaro ◽  
Vinny Chandran Suja ◽  
Aadithya Kannan ◽  
Luigi Davide Gala ◽  
Ernesto Di Maio ◽  
...  
Keyword(s):  
Surface Energy ◽  
Liquid Film ◽  
Bubble Dynamics ◽  
Characteristic Length ◽  
Industrial Processes ◽  
Viscous Forces ◽  
Bubble Bursting ◽  
Impact Phenomena ◽  
Simple Modeling

The lifetime of bubbles, from formation to rupture, attracts attention because bubbles are often present in natural and industrial processes, and their geometry, drainage, coarsening, and rupture strongly affect those operations. Bubble rupture happens rapidly, and it may generate a cascade of small droplets or bubbles. Once a hole is nucleated within a bubble, it opens up with a variety of shapes and velocities depending on the liquid properties. A range of bubble rupture modes are reported in literature in which the reduction of a surface energy drives the rupture against inertial and viscous forces. The role of surface viscoelasticity of the liquid film in this colorful scenario is, however, still unknown. We found that the presence of interfacial viscoelasticity has a profound effect in the bubble bursting dynamics. Indeed, we observed different bubble bursting mechanisms upon the transition from viscous-controlled to surface viscoelasticity-controlled rupture. When this transition occurs, a bursting bubble resembling the blooming of a flower is observed. A simple modeling argument is proposed, leading to the prediction of the characteristic length scales and the number and shape of the bubble flower petals, thus paving the way for the control of liquid formulations with surface viscoelasticity as a key ingredient. These findings can have important implications in the study of bubble dynamics, with consequences for the numerous processes involving bubble rupture. Bubble flowering can indeed impact phenomena such as the spreading of nutrients in nature or the life of cells in bioreactors.

scholarly journals On the origin of the circular hydraulic jump in a thin liquid film

2018 ◽  
Vol 851 ◽  
Author(s):  
Rajesh K. Bhagat ◽  
N. K. Jha ◽  
P. F. Linden ◽  
D. Ian Wilson
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Capillary Waves ◽  
Hydraulic Jumps ◽  
Planar Surface ◽  
Normal Impact ◽  
Viscous Forces

This study explores the formation of circular thin-film hydraulic jumps caused by the normal impact of a jet on an infinite planar surface. For more than a century, it has been believed that all hydraulic jumps are created due to gravity. However, we show that these thin-film hydraulic jumps result from energy loss due to surface tension and viscous forces alone. We show that, at the jump, surface tension and viscous forces balance the momentum in the liquid film and gravity plays no significant role. Experiments show no dependence on the orientation of the surface and a scaling relation balancing viscous forces and surface tension collapses the experimental data. A theoretical analysis shows that the downstream transport of surface energy is the previously neglected critical ingredient in these flows, and that capillary waves play the role of gravity waves in a traditional jump in demarcating the transition from the supercritical to subcritical flow associated with these jumps.

Vibration of spinning discs and powder formation in centrifugal atomization

2010 ◽  
Vol 467 (2126) ◽  
pp. 361-380 ◽  
Author(s):  
Huaxia Deng ◽  
Huajiang Ouyang
Keyword(s):  
Liquid Film ◽  
Spray Deposition ◽  
Moving Load ◽  
Experimental Results ◽  
Industrial Processes ◽  
Powder Size ◽  
Centrifugal Atomization ◽  
Powder Formation ◽  
Spinning Disc

Spinning discs with liquid film on the surface have numerous applications in many industrial processes and have attracted a lot of investigations. Centrifugal atomization of metallic melts using a spinning disc is an efficient process for powder production and spray deposition, which is a typical example of a spinning disc interacting with a liquid film. In this paper, the vibration of an atomizing disc excited by a moving melt is analysed and the role of vibration in the disintegration of the melt film on atomizing discs is then investigated. A dynamic model of the atomizing disc as a spinning Kirchhoff plate is established with moving melt film treated as a moving load on the disc and as an unstable growing wave interacting with the surrounding air outside the disc. The powder size is analysed theoretically and then compared with experimental results. It is found that the predicted results agree with the experimental results very well in the film disintegration mode. Furthermore, the influences of the atomizer parameters on the melt break up and powder size are discussed. The control parameters in the centrifugal atomization are identified, which can provide guidance for atomizer designs.

scholarly journals Dynamics of Monolayer Growth in Vapor–Liquid–Solid GaAs Nanowires Based on Surface Energy Minimization

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1681
Author(s):  
Hadi Hijazi ◽  
Vladimir G. Dubrovskii
Keyword(s):  
Surface Energy ◽  
Continuous Process ◽  
Vapor Liquid Solid ◽  
Gaas Nanowires ◽  
Monolayer Growth ◽  
Surface Energetics ◽  
Monolayer Expansion ◽  
Vapor Liquid Solid Growth ◽  
Vapor Liquid

The vapor–liquid–solid growth of III-V nanowires proceeds via the mononuclear regime, where only one island nucleates in each nanowire monolayer. The expansion of the monolayer is governed by the surface energetics depending on the monolayer size. Here, we study theoretically the role of surface energy in determining the monolayer morphology at a given coverage. The optimal monolayer configuration is obtained by minimizing the surface energy at different coverages for a set of energetic constants relevant for GaAs nanowires. In contrast to what has been assumed so far in the growth modeling of III-V nanowires, we find that the monolayer expansion may not be a continuous process. Rather, some portions of the already formed monolayer may dissolve on one of its sides, with simultaneous growth proceeding on the other side. These results are important for fundamental understanding of vapor–liquid–solid growth at the atomic level and have potential impacts on the statistics within the nanowire ensembles, crystal phase, and doping properties of III-V nanowires.

Preferred Orientations for Sol-Gel Derived Plzt Thin Layers

1993 ◽  
Vol 310 ◽  
Author(s):  
Toshihiko Tani ◽  
Zhengkui Xu ◽  
David A. Payne
Keyword(s):  
Heat Treatment ◽  
Surface Energy ◽  
Sol Gel ◽  
Nucleation And Growth ◽  
Thin Layers ◽  
Energy Conditions ◽  
Chemical Characteristics ◽  
Interfacial Chemistry ◽  
Si Substrates

AbstractPLZT thin layers were deposited onto various substrates by sol-gel methods, and crystallized under different conditions and substrate treatments. Relationships are given for the chemical characteristics of the substrate's surface and the preferred orientations which develop on heat treatment. A preferred (111) orientation always developed for perovskite crystallized on Pt layers which contained Ti on the surface. This was attributed to the formation of Pt3Ti and the role of heteroepitaxial nucleation and growth sites. In addition, a preferred (100) orientation was also obtained on unannealed Pt/Ti/SiO2/Si substrates which were free of Ti on the surface. This was attributed to self-textured growth with flat faces striving for minimum surface energy conditions. The results are discussed in terms of the importance of interfacial chemistry on the control of texture for crystallization of PLZT thin layers on coated substrates.

scholarly journals Simple Modeling of the Ratio of Fields at a Tip and a Contacting Surface with External Illumination

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
E. Bortchagovsky
Keyword(s):  
External Field ◽  
Raman Scattering ◽  
External Excitation ◽  
Exciting Field ◽  
Rayleigh Approximation ◽  
Surface Configuration ◽  
Standard Configuration ◽  
Enhanced Raman Scattering ◽  
Simple Modeling

The analysis of the relation of fields generated at a tip and a contacting surface is performed in the Rayleigh approximation of a simple dipole model for the standard configuration of tip-enhanced Raman scattering experiments with external excitation. A comparison of the present results with the previous ones obtained for the case of tip-source reveals the role of tip-surface configuration as the amplifier of the exciting field and the stronger influence of roughness on the field distribution at external illumination, as roughness is directly excited by the external field producing second source of field in addition to the tip.

Role of surface energy in the heating mechanism of high explosives (HE) under shock effects

1982 ◽  
Vol 17 (5) ◽  
pp. 581-583
Author(s):  
E. G. Baranov ◽  
O. N. Oberemok ◽  
E. A. Semenyuk
Keyword(s):  
Surface Energy ◽  
High Explosives ◽  
Heating Mechanism

scholarly journals The history effect in bubble growth and dissolution. Part 1. Theory

2016 ◽  
Vol 800 ◽  
pp. 180-212 ◽  
Author(s):  
Pablo Peñas-López ◽  
Miguel A. Parrales ◽  
Javier Rodríguez-Rodríguez ◽  
Devaraj van der Meer
Keyword(s):  
Bubble Dynamics ◽  
Ambient Pressure ◽  
Time History ◽  
Interfacial Concentration ◽  
Interface Concentration ◽  
Governing Differential Equation ◽  
History Of ◽  
History Effect ◽  
Isothermal Regime

The term ‘history effect’ refers to the contribution of any past mass transfer events between a gas bubble and its liquid surroundings towards the current diffusion-driven growth or dissolution dynamics of that same bubble. The history effect arises from the (non-instantaneous) development of the dissolved gas concentration boundary layer in the liquid in response to changes in the concentration at the bubble interface caused, for instance, by variations of the ambient pressure in time. Essentially, the history effect amounts to the acknowledgement that at any given time the mass flux across the bubble is conditioned by the preceding time history of the concentration at the bubble boundary. Considering the canonical problem of an isolated spherical bubble at rest, we show that the contribution of the history effect in the current interfacial concentration gradient is fully contained within a memory integral of the interface concentration. Retaining this integral term, we formulate a governing differential equation for the bubble dynamics, analogous to the well-known Epstein–Plesset solution. Our equation does not make use of the quasi-static radius approximation. An analytical solution is presented for the case of multiple step-like jumps in pressure. The nature and relevance of the history effect is then assessed through illustrative examples. Finally, we investigate the role of the history effect in rectified diffusion for a bubble that pulsates under harmonic pressure forcing in the non-inertial, isothermal regime.

Experimental Observation of Nucleate Boiling Entrainment in a Liquid Film

2021 ◽  
Author(s):  
Junpei Tabuchi ◽  
Yuki Narushima ◽  
Kenichi Katono ◽  
Tomio Okawa
Keyword(s):  
Liquid Film ◽  
Forced Convection ◽  
Vapor Bubble ◽  
Water Surface ◽  
Annular Flow ◽  
Nucleate Boiling ◽  
Vapor Bubbles ◽  
Droplet Entrainment ◽  
Bubble Bursting ◽  
Filament Breakup

Abstract Many studies have been conducted on droplet entrainment in an annular flow regime, but little is known about droplet entrainment caused by nucleate boiling. In this report, visualization results of droplet entrainment caused by nucleate boiling are described. We observed two processes of droplet entrainment. The first one causes bubble bursting at a water surface. The second one causes filament breakup which occurs when the vapor bubble reaches and collapses at the interface between air and liquid. From comparison of the phenomena for the two processes, we found that the diameters of the droplets and vapor bubbles were considerably different. Using the results of this research allows the effect of forced convection to be taken into account. In the future, we plan to expand the amount of data and develop a boiling entrainment model under forced convection conditions.

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