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Visualizzazione dei post in ordine di pertinenza per la query drops. Ordina per data Mostra tutti i post
Visualizzazione dei post in ordine di pertinenza per la query drops. Ordina per data Mostra tutti i post

martedì 30 gennaio 2024

# gst: analogy between quasi-2D and 3D liquid drops.

<< Liquid drops are everywhere around us and important in numerous technological applications. Here, (AA) demonstrate a quasi-two-dimensional (Q2D) analogy to the regular, often close to axisymmetric, three-dimensional (3D) drops. >>️

<< The Q2D drops are created by confining liquids between vertical walls, leading to formation of low aspect ratio capillary bridges that are deformed by gravity. When stationary, the Q2D drops adopt projected shapes that are analogous to 3D sessile drops, ranging from circular drops to puddles. >>️

<< When moving, the Q2D drops exhibit capillary and fluid mechanical behaviours analogous to 3D drops, including impacts and sliding on pseudo-surfaces. The Q2D drops also exhibit considerably more complex phenomena such as levitation, instabilities and pattern formation when subjected to external electric, magnetic and flow fields -- all seen also in regular 3D drops. >>️

<< 3D-Q2D analogy suggests that the diverse and often complicated phenomena observed in 3D drops can be studied in the Q2D geometry, >>
Tytti Kärki, Into Pääkkönen, et al. Quasi-Two-Dimensional Drops. arXiv: 2401.11845v1 [physics.flu-dyn]. Jan 22, 2024.

Also: drop, analogy, in https://www.inkgmr.net/kwrds.html

Keywords: gst, drop, droplet, droploid, analogy


lunedì 8 aprile 2024

# gst: apropos of evaporation, puncturing of active drops

<< By virtue of self-propulsion, active particles impart intricate stresses to the background fluids. (..) this active stress can be utilized to greatly control evaporation dynamics of active drops. >>

AA << discover a new phenomenon of puncturing of the active drops, where the air-liquid interface of the drop undergoes spontaneous tearing and there occurs a formation of a new three-phase contact line due to the liquid-air interface hitting the liquid-solid interface through evaporation-driven mass loss. Post puncturing, (AA) see an inside-out evaporation of the drop, where the new contact line sweeps towards the pinned outer contact line of the drops, contrasting regular drops that straightaway shrink to zero volume with self-similar shape. >>

<< Furthermore, (..) the activity inside the drops can manipulate the three-phase contact-line dynamics, which for contractile drops can result in an up to 50% enhanced lifetime of the drop and 33% quicker evaporation for extensile drops. By analyzing the flux distribution inside the drop, (AA) gain insights on nonintuitive deposition patterns (e.g., ring galaxy type deposits that demonstrate controllable spatial gradients in the concentrations of the deposited particles) of active particles, which are oftentimes biological substances or bimetallic nanoparticles of interest. >>

Ghansham Rajendrasingh Chandel, Vishal Sankar Sivasankar, Siddhartha Das. Evaporation of active drops: Puncturing drops and particle deposits of ring galaxy patterns. Phys. Rev. Fluids 9, 033603. Mar 27, 2024. 

Also: drop, particle, evaporation, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, particle, evaporation, transition, drop interactions, droplet, droploid


lunedì 25 novembre 2024

# gst: apropos of dances, drops that dance following snake- and ouroboros-shaped trajectories on lubricated surfaces.


<< Recently, (AA) observed a curious breath figure pattern when water condenses on solid surfaces coated with a thin lubricant oil film. Water drops of various sizes, ranging from tens of microns to several millimetres, start to perform a self-avoiding, serpentinelike dance. As the drop moves, it consumes smaller droplets along its path, converting interfacial energy into kinetic energy to sustain its motion. These self-avoiding drops preferentially avoid crossing their own paths as well as the paths of other drops; they can only intersect their previous paths once sufficient recondensation has occurred. This self-avoiding behavior arises because the previous path (..) contains little to no water content to fuel self-propulsion, so the drops continually seek areas with higher local water content. >>️

<< This intricate serpentine dance is driven by short-range interactions between droplets, mediated by overlapping menisci, similar to the Cheerios effect. Remarkably, long-range order spontaneously emerges from these short-range interactions, with the collective motion exhibiting self-similarity—breath figure patterns appear roughly similar across different scales. >>

<< The serpentine motions of the drops, which can span distances many times their diameters, eventually deplete the local lubricant film, causing a transition from serpentine to circular motion. This circular motion can be seen as a unique form of serpentine motion occurring in lubricant-poor regions. As the drops move, they continually redistribute the lubricant across the substrate, leading to a dynamic interplay between serpentine and circular motions. This ongoing redistribution can be visualized by illuminating the surface with diffused white light and capturing the resulting interference patterns with a digital camera. Variations in lubricant thickness produce different hues, creating a vibrant, colorful canvas and an intricate dance floor for the condensing drops. >>️

<< The phenomenon described in (AA) paper represents a fascinating example of active matter driven by condensation, rather than the more commonly observed chemical reactions or Marangoni effects. >>

Marcus Lin, Fauzia Wardani, Dan Daniel. Dancing drops on lubricated surfaces. Phys. Rev. Fluids 9, 110504. Nov 22, 2024.

Marcus Lin, Solomon Adera, Joanna Aizenberg, Yao Xi, Dan Daniel. V0030: Serpents and Ouroboros: Emergent collective motion of condensate droplets. 76th Annual Meeting of the APS Division of Fluid Dynamics. Nov 19-21, 2023.

Also: drop, droplet, droploid, dance, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, droplet, droploid, dance


venerdì 15 marzo 2024

# gst: multi-component droplets may exhibit self-lubricating effects

<< Over the past decade, there has been a growing interest in the study of multicomponent drops. These drops exhibit unique phenomena, as the interplay between hydrodynamics and the evolving physicochemical properties of the mixture gives rise to distinct and often unregulated behaviors. >>

<< Of particular interest is the complex dynamic behavior of the drop contact line, which can display self-lubrication effect. The presence of a slipping contact line in self-lubricating multicomponent drops can suppress the coffee-stain effect, conferring valuable technological applications. >>

Huanshu Tan, Detlef Lohse, Xuehua Zhang. Self-Lubricating Drops. arXiv: 2403.01207v1 [physics.flu-dyn]. Mar 2, 2024

Also: drop droplet droploid, in https://www.inkgmr.net/kwrds.html

Keywords: drop, droplet, droploid, multicomponent drops, drop contact line, self-lubrication



mercoledì 21 giugno 2023

# gst: nonmonotonic appearance- disappearance behaviors of two unequal-sized miscible liquid drops

<< the coalescence process of two miscible liquid drops exhibits a nonmonotonic behavior of partial coalescence from appearance to disappearance and then reappearance with decreasing surface tension ratio. The strong lifting force of the intense Marangoni flow causes the reappearance of partial coalescence at higher surface tension difference between two drops. When the Ohnesorge number increases, high viscous forces restrict the propagation of Marangoni flow and do not favor the pinch-off, even in the presence of a significant surface tension difference. The generation of secondary drops at a considerable surface tension difference is also prevented for small parent drop size ratio. >>️

Swati Singh, Arun K. Saha. Effect of surface tension gradients on coalescence dynamics of two unequal-sized drops. Phys. Rev. Fluids 8, 053604. May 24, 2023. 

Also:  'drop' in https://www.inkgmr.net/kwrds.html  

Keywords: gst, behavior, drop, drop breakup, drop coalescence, drop interactions, droplet, droploid


mercoledì 14 giugno 2023

# gst: apropos of transitions, droplet trajectories during single and collective bursting bubbles

<< Mechanisms of droplet production from bursting bubbles have been extensively studied for single bubbles, but remain sparsely investigated in more complex collective settings. >>️

<< In the collective bubbling experiment, subsurface quasimonodisperse bubbles are rising up to the surface where, depending on the surfactant concentration, they can either merge or assemble in rafts of monodisperse bubbles. Drop trajectories are recorded, analyzed, and shown to exhibit uniquely distinctive features for the different production mechanisms: centrifuge film drops are ejected sideways, and jet drops are ejected vertically. Different single-burst scalings are finally compared to the experimental size-velocity relationships, and reveal that drops coming from collective bubble bursting appear slower and more scattered than when coming from single bursting bubbles. >>️

B. Neel and L. Deike. Velocity and size quantification of drops in single and collective bursting bubbles experiments. Phys. Rev. Fluids 7, 103603. Oct 5, 2022. 

Also: 'when a superbubble can generate trains of shock waves'. Mar 6, 2019.

Also: 'transition', 'droplet', 'droploid', 'bubble', in: https://www.inkgmr.net/kwrds.html

Keywords: gst, transition, drop, droplet, droploid, bubble, collective dynamics,  fluid dynamics

PS: << they can either merge or assemble in rafts of monodisperse bubbles >> ; this is poetry, without unnecessary adjectives, anzicheforse ... FonT. Wed June 14, 2023 16:58 (cest)


mercoledì 15 febbraio 2023

# gst: when a soliton juggles ('catches' and 'throws') droplets


<< Jugglers normally work with solid objects, but a research team has now demonstrated a system that juggles liquid drops. (AA)  have previously shown that liquid drops can bounce in place above the surface of the same liquid—or bounce while moving across the surface—if the container is continuously vibrated (..) In these past experiments, the surface was nearly flat, except for waves generated by the bouncing drop. In the new work by undergraduate student Camila Sandivari of the University of Chile and her colleagues, the vibrations cause the liquid surface to form a large standing wave that actively “catches” and “throws” the drop during each cycle of its oscillation. The trapping of the drop is similar in principle to other types of wave traps, such as laser-based optical tweezers, and the system could potentially lead to new types of traps for larger objects. >>

AA << placed water mixed with a dye and a surface-tension-reducing agent in a 20-cm-long, 2.6-cm-wide basin that supports an unusual type of surface wave when the basin is vibrated in a specific frequency range. In this wave, rather than a series of oscillating peaks and valleys, there is only a single standing wave peak, called a soliton. However, this peak doesn’t oscillate uniformly across the basin’s short dimension (the width). A peak appears at one of the long walls coincident with a valley at the opposite wall, and then the peak and the valley switch places moments later, keeping a relatively flat “node” line along the central long axis of the basin. >>

AA << used a pipette to place a few-millimeter-wide drop of the same fluid just above the oscillating soliton, close to one of the long walls, and found that drops could be juggled for up to 90 minutes. The team attributes this unusual stability in part to a property of the soliton: if the drop wanders off-center, the oscillating surface wave pulls it back toward its center, similar to the way the laser field in optical tweezers is able to stably hold a small particle at its center. >>

David Ehrenstein. Juggling Water Drops. Physics 16, 21. Feb 10, 2023. 
https://physics.aps.org/articles/v16/21

Also

keyword 'drop' | 'droplet' | 'droploids' in FonT




keyword 'goccia' in Notes 
(quasi-stochastic poetry)


keyword 'solitons' in FonT



Keywords: gst, solitons, drop, droplet, droploids, goccia


venerdì 4 febbraio 2022

# gst: apropos of apparent erratic dynamics, the self-organization of drops bouncing on a vertically-vibrated surface

<< A drop bouncing on a vertically-vibrated surface may self-propel forward by Faraday waves and travels along a fluid interface. >>

<< A fine anal­ysis of the pairwise density function shows that while being dynamic, time-evolving and presenting many in­dications of a good mixing in the phase space, the sys­tem adopts in average preferred distances which origin has been rationalized by analysing the internal symme­try of the waves. Thus (AA) have shed light numerically on a statistical many-body wave self-organisation in an apparent erratic dynamics. >>

Adrien Hélias, Matthieu Labousse. Statistical self-organization of walking drops. arXiv:2201.07689v1 [cond-mat.soft]. Jan 19, 2022.


Also

keywords: gst, drops, self-organization, erratic dynamics, erraticity



sabato 1 agosto 2020

# GST: how to harvest energy from impacting droplets

AA << designed an electrical generator that can harvest energy from impacting droplets and other sources of mechanical energy. (..) The electrical generator can be explained as being a permanently charged capacitor, also known as an electret. >>

They << managed to convert 11.8% of the mechanical energy of an impacting droplet into electrical energy, which is a significant improvement compared to the efficiency of similar devices. Furthermore, they demonstrated that the energy harvesting efficiency does not degrade after 100 days, requiring only a single 15 minute charging cycle before long-term application. >>

K.W. Wesselink. Generator developed for harvesting energy from droplets. 
University of Twente. Jul 8, 2020.


Hao Wu, Niels Mendel, et al. Charge Trapping‐Based Electricity Generator (CTEG): An Ultrarobust and High Efficiency Nanogenerator for Energy Harvesting from Water Droplets. Advanced Materials. doi: 10.1002/ adma.202001699. July 6, 2020.


Hao Wu, Niels Mendel, et al. Energy harvesting from drops impacting onto charged surfaces. Phys. Rev. Lett. Jun 25, 2020.


Also





giovedì 31 ottobre 2019

# gst: spontaneous spin-sliding of volatile drops

<< When a volatile solvent droplet is deposited on a freely floating swellable sheet, it can spontaneously become lobed, asymmetric, and either spin, slide or move via a combination of the two.  This process of symmetry-breaking is a consequence of the solvent droplet swelling the membrane and its inhomogeneous evaporation from the membrane, coupled with the hydrodynamics within the droplet. By tuning the membrane thickness and the droplet size, (AA) find a critical threshold that determines the transition from a quiescent spherical cap state to a self-piloted motile state.>>

Aditi Chakrabarti, Gary P. T. Choi, L. Mahadevan. Spontaneous spin-sliding of volatile drops on swelling sheets. arXiv:1910.07064v1 [cond-mat.soft]  Oct 15, 2019. 

https://arxiv.org/abs/1910.07064   

sabato 24 agosto 2019

# gst: active drops: from steady to chaotic self-propulsion

<< Individual chemically active drops suspended in a surfactant solution were observed to self-propel spontaneously with straight, helical, or chaotic trajectories. (..) strong advection (e.g., large droplet size) may destabilize a steadily self-propelling drop; once destabilized, the droplet spontaneously stops and a symmetric extensile flow emerges. If advection is strengthened even further in comparison with molecular diffusion, the droplet may perform chaotic oscillations. >>

Matvey Morozov, Sebastien Michelin. Nonlinear dynamics of a chemically-active drop: From steady to chaotic self-propulsion. J. Chem. Phys. 150, 044110 (2019). doi: 10.1063/1.5080539. Jan 31, 2019.  https://aip.scitation.org/doi/10.1063/1.5080539



martedì 14 novembre 2017

# gst: a striking analogy between solid–solid and solid–drop frictions

AA << report that the lateral adhesion force between a liquid drop and a solid can also be divided into a static and a kinetic regime. This striking analogy with solid–solid friction is a generic phenomenon that holds for liquids of different polarities and surface tensions on smooth, rough and structured surfaces >>

Nan Gao, Florian Geyer, et al. How drops start sliding over solid surfaces. Nature Physics doi: 10.1038/nphys4305 Nov 6, 2017

https://www.nature.com/articles/nphys4305

AA << acknowledges that their experiments are just the beginning in trying to fully understand the nature of friction between drops and solid objects >>

Bob Yirka. Droplet friction found to be similar to that of solid objects. Nov 8, 2017

https://m.phys.org/news/2017-11-droplet-friction-similar-solid.html

giovedì 17 ottobre 2019

# gst: fingerprints of reality (2): the stormquake

AA << find that during large storms such as hurricanes and Nor'easters the interaction of long‐period ocean waves with shallow seafloor features located near the edge of continental shelves, known as ocean banks, excites coherent transcontinental Rayleigh wave packets in the 20 to 50 s period band. These "stormquakes" migrate coincident with the storms, but are effectively spatiotemporally focused seismic point sources with equivalent earthquake magnitudes that can be greater than 3.5. >>

Wenyuan Fan, Jeffrey J. McGuire, et al. Stormquakes. Geophysical Research Letters. Oct 14, 2019.    https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084217  

Strong storms generating earthquake-like seismic activity. Florida State University. Oct 15, 2019.    https://m.phys.org/news/2019-10-strong-storms-earthquake-like-seismic.html 

Also  

fingerprints of reality: water drops that vibrate, flames that oscillate, and viscous fluids that form rivulets ...

domenica 9 dicembre 2018

# gst: fingerprints of reality: water drops that vibrate, flames that oscillate, and viscous fluids that form rivulets ...

<< In one of this year’s three winning videos, a drop of blue-dyed water at the bottom of an anise-oil and alcohol mixture begins to grow and shake, eventually pinching off a fragment that floats up. The process repeats several times. Created by now four-time Gallery-of-Fluid-Motion winner Oscar Enríquez of Carlos III University of Madrid and his colleagues, the visuals are accompanied by a soundtrack featuring a musical improvisation by a trio consisting of Enríquez on percussion, a violinist, and a clarinetist. Each instrument in the trio represents one of the three fluids. >>

Award-Winning Fluid Videos. APS. Physics 11, 121. Nov 21, 2018.

https://physics.aps.org/articles/v11/121

mercoledì 28 agosto 2024

# gst: dynamics of small droplets in turbulent multiphase flows


AA << show unambiguously that the formation of small droplets is governed by the internal dynamics which occurs during the breakup of large drops and that the high vorticity and the extreme dissipation associated to these events are the consequence and not the cause of the breakup. >>️

M. Crialesi-Esposito, G. Boffetta, L. Brandt, et al. How small droplets form in turbulent multiphase flows. Phys. Rev. Fluids 9, L072301. Jul 29, 2024. 

Also: drop, bubble, transition, turbulence, intermittency, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drop, droplet, droploid,  bubble, transition, turbulence, intermittency


sabato 8 marzo 2025

# gst: 'jazzy' intermittency, its onset and multiscaling in active turbulence.

<< Recent results suggest that highly active, chaotic, nonequilibrium states of living fluids might share much in common with high Reynolds number, inertial turbulence. (AA) now show, by using a hydrodynamical model, the onset of intermittency and the consequent multiscaling of Eulerian and Lagrangian structure functions as a function of the bacterial activity. (Their) results bridge the worlds of low and high Reynolds number flows as well as open up intriguing possibilities of what makes flows intermittent. >>️

AA << believe that (Their) work significantly understands the dynamics of dense bacterial suspensions in ways which isolates the truly turbulent effects from those stemming from simpler chaotic motion. More intriguingly, and at a broader conceptual framework, this study yet again underlines that intermittency can be an emergent phenomena in flows where the nonlinearity does not, trivially, dominate the viscous damping. Indeed, there is increasing evidence of intermittency emerging in systems which are not turbulent in the classical sense. Examples include flows with modest Reynolds number of∼O(10e2) showing intermittent behaviour characteristic of high Reynolds turbulence, self-propelling active droplets with intermittent fluctuations, active matter systems of self-propelled particles, which undergo a glass transition, with an intermittent phase before dynamical arrest, and perhaps most pertinently, in elastic turbulence. Thus, (AA) believe, (Their) work will contribute further to understanding what causes flows to turn intermittent. Answers to such questions will also help in understanding fundamental questions in high Reynolds number turbulence. >>️

Kolluru Venkata Kiran, Kunal Kumar, et al. Onset of Intermittency and Multiscaling in Active Turbulence. Phys. Rev. Lett. 134, 088302. Feb 28, 2025. 

Also: intermittency, transition, fluctuations, drop, droplet, droploid, elastic, turbulence, chaos, jazz, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, intermittency, transitions, fluctuations, drops, droplets, droploids, elasticity, turbulence, chaos, jazz


giovedì 7 giugno 2018

# drugs: the sweet side of a snake venom (B. jararaca)

AA << report on the sweet side of snake venom toxins >>

<< most proteins in lancehead venom are modified with glycans, which can affect the proteins' folding, stability and binding >>

<< Glycans containing sialic acid may help in venom solubility and increase toxin half-life >>

<< Sialic acid on a toxic enzyme may also bind to host proteins called siglecs [sialic acid-binding Ig superfamily  lectins], pulling the enzyme closer to target cells for greater effect >>

How just drops of viper venom pack a deadly punch. Am Soc for Biochem and Molec Biol. Jun 1, 2018.

https://m.phys.org/news/2018-06-viper-venom-deadly.html

Debora Andrade-Silva, David Ashline, et al. Structures of N-Glycans of Bothrops venoms revealed as molecular signatures that contribute to venom phenotype in viperid snakes. Molecular & Cellular Proteomics. doi: 10.1074/mcp.RA118.000748 mcp.RA118.000748. May 1, 2018.

http://m.mcponline.org/content/early/2018/04/30/mcp.RA118.000748

mercoledì 10 aprile 2024

# gst: exploring the on-demand dynamical generation of a plethora of dispersive shock waves arising in attractive one-dimensional droplet-bearing environment.

AA << demonstrate the controllable generation of distinct types of dispersive shock-waves emerging in a quantum droplet bearing environment with the aid of step-like initial conditions. Dispersive regularization of the ensuing hydrodynamic singularities occurs due to the competition between meanfield repulsion and attractive quantum fluctuations. This interplay delineates the dominance of defocusing (hyperbolic) and focusing (elliptic) hydrodynamic phenomena respectively being designated by real and imaginary speed of sound. >>

<< Surprisingly, dispersive shock waves persist across the hyperbolic-to-elliptic threshold, while a plethora of additional wave patterns arise, such as rarefaction waves, traveling dispersive shock waves, (anti)kinks and droplet wavetrains. >>

AA << results pave the way for unveiling a multitude of unexplored coherently propagating waveforms in such attractively interacting mixtures. >>

Sathyanarayanan Chandramouli, Simeon I. Mistakidis, Garyfallia C. Katsimiga, Panayotis G. Kevrekidis. 
Dispersive shock waves in a one-dimensional droplet-bearing environment. arXiv: 2404.02998v2 [nlin.PS]. Apr 5, 2024. 

Also: waves, drop, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, waves, drops 


sabato 4 gennaio 2025

# gst: floating droplets excited with Faraday waves

<< The Faraday instability has been extensively studied in bounded containers but only recently has research on this phenomenon in flexible domains been conducted. (AA) study floating liquid droplets with Faraday waves excited on their surface, which undergo a slow time evolution toward a stable noncircular shape. (AA) develop a theoretical model for the evolution of the boundary of the droplet, thus allowing to simulate its full transient motion toward steady state. >>

<< By changing the forcing frequency and amplitude of (the) system, (They) observe a variety of stable droplet shapes. (..) Interesting transient behavior such as hysteresis is also discussed, where the final droplet shape depends on its previous shape. Finally, (They) touch upon droplets that do not reach a steady state shape, instead oscillating periodically in time or rotating at a constant angular velocity. >>️

L. Mazereeuw. Theoretical and experimental investigation of the shapes formed by floating droplets excited with Faraday waves. Phys. Rev. Fluids 9, 124404. Dec 19, 2024.

Also: drop, waves, instability, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: drops, droplets, droploids, waves, instability, Faraday instability, transitions   


domenica 8 dicembre 2024

# gst: apropos of puddles, how to design and stabilize a Leidenfrost puddle

<< Leidenfrost puddles exhibit erratic bubble bursts that release vapor trapped beneath the liquid, becoming amorphous and unstable. (AA) report a method to stabilize and design a Leidenfrost puddle. >>

<< When a thin hydrophilic layer with a suitable design is placed over the liquid, the puddle adopts the layer shape due to adhesive forces and becomes stable. (AA) show a variety of puddle designs with the required layer dimensions to avoid vapor accumulation, as well as wetting and buoyancy conditions. >>

<< With the layer, the puddle evaporation rate increases significantly and can be modified by varying the layer dimensions. Finally, an illustrative use of this method in a cooling process is presented. >>️

F. Pacheco-Vázquez, M. Aguilar-González, L. Victoria-García. Designing Leidenfrost Puddles. Phys. Rev. Lett. 133, 234001. Dec 4, 2024. 

Also: drop, bubble, instabilitytransition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, drops, bubbles, instability, transition