# gst: the way bubbles gallop.

<< ️Bubbles are more than fleeting pockets of air trapped in liquid: they exhibit an ever-expanding repertoire of intriguing behaviors. From da Vinci's sketches of their swirling paths to modern-day studies of their erratic dances under acoustic waves, the rich dynamics of bubbles have long captured the attention of everyday observers, engineers, and scientists alike. When exposed to periodic sound waves, bubbles can shift from regular pulsations to rapid zigzagging, mimicking the randomness of Brownian motion. Under sudden pressure changes, they may collapse violently, producing cavitation—intense shock waves capable of damaging solid surfaces. In extreme cases, the implosion may become so intense that the bubble emits a spark of light. >>

<< ️Bubbles can also challenge common intuition: they may appear to violate Archimedes' principle, sinking against gravity in oscillating fluids, and carbonated drinks. Despite centuries of explorations, new and often surprising bubble phenomena continue to emerge. One such example is the recently discovered “galloping” bubble, introduced in (AA) recent publication. Here, (They) showcase this new mechanism of bubble locomotion, highlighting its rich dynamics and striking visual appeal. >>

Jian H. Guan, Saiful I. Tamim, Connor W. Magoon, et al. The way bubbles gallop. Phys. Rev. Fluids 10, 110507. Nov 20, 2025.

https://journals.aps.org/prfluids/abstract/10.1103/fbdh-fnzv

Gallery of Fluid Motion. https://doi.org/10.1103/APS.DFD.2024.GFM.V2684816

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

Keywords: gst, bubble, galloping bubbles, galloping threshold, galloping motion, galloping mechanism, instability, galloping instability, drops, droplets, droploids, transitions.

# gst: experimental observation of hidden multistability in nonlinear systems.

<< ️Multistability, the coexistence of multiple stable states, is a cornerstone of nonlinear dynamical systems, governing their equilibrium, tunability, and emergent complexity. Recently, the concept of hidden multistability, where certain stable states evade detection via conventional continuous parameter sweeping, has garnered increasing attention due to its elusive nature and promising applications.  >>

<< ️In this Letter, (AA) present the first experimental observation of hidden multistability using a programmable acoustic coupled-cavity platform that integrates competing self-focusing and self-defocusing Kerr nonlinearities. Beyond established bistability, (They) demonstrate semi- and fully-hidden tristabilities by precisely programming system parameters. Crucially, the hidden stable states, typically inaccessible via the traditional protocol, are unambiguously revealed and dynamically controlled through pulsed excitation, enabling flexible transitions between distinct types of stable states. >>

Kun Zhang, Qicheng Zhang, Shuaishuai Tong, et al. Experimental Observation of Hidden Multistability in Nonlinear Systems. arXiv: 2511.04150v1 [nlin.CD]. Nov 6, 2025.

https://arxiv.org/abs/2511.04150

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

Keywords: gst, stability, multistability, hidden multistability, semi- fully-hidden tristabilities, pulsed excitation.

# gst: apropos of the transition of order from chaos, a universal behavior near a critical point.

<< As the Reynolds number is increased, a laminar fluid flow becomes turbulent, and the range of time and length scales associated with the flow increases. Yet, in a turbulent reactive flow system, as we increase the Reynolds number, (AA) observe the emergence of a single dominant timescale in the acoustic pressure fluctuations, as indicated by its loss of multifractality. >>️

AA << study the evolution of short-time correlated dynamics between the acoustic field and the flame in the spatiotemporal domain of the system.   >>️

<< the susceptibility of the order parameter, correlation length, and correlation time diverge at a critical point between chaos and order. (AA) results show that the observed emergence of order from chaos is a continuous phase transition (..) the critical exponents characterizing this transition fall in the universality class of directed percolation. >>️

The << paper demonstrates how a real-world complex, nonequilibrium turbulent reactive flow system exhibits universal behavior near a critical point. >>️

Sivakumar Sudarsanan, Amitesh Roy, et al. Emergence of order from chaos through a continuous phase transition in a turbulent reactive flow system. Phys. Rev. E 109, 064214. Jun 20, 2024. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.064214

Also: order, chaos, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, order, chaos, transition 

# gst: apropos of synchronization of large bubble clouds, self-oscillating acoustic bubbles that bounce

<< Self-oscillations underlie many natural phenomena such as heartbeat, ocean waves, and the pulsation of variable stars. (..) In this study, (AA) consider two closely spaced bubbles pulsating in the kHz range in response to ultrasonic excitation. A translational bouncing motion emerges from their interaction with a much lower frequency than the bubble pulsation frequency. >>

Their analysis << reveals that the observed bubble bouncing exhibits the main features of self-oscillation, such as negative damping and the emergence of a limit cycle. These results highlight unexpected nonlinear effects in the field of microbubbles and give insights into the understanding of synchronization in large bubble clouds. >>️

Gabriel Regnault, Alexander A Doinikov, et al. Phenomenon of self-oscillation in bubble dynamics: Bouncing acoustic bubbles. arXiv: 2404.05822v1 [physics.flu-dyn]. Apr 8, 2024.

https://arxiv.org/abs/2404.05822

Also: bubble, bouncing, behav, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, bubble, self-oscillation, bouncing, behavior, collective behavior, bouncing motion, synchronization

# gst: myriad of complex dynamics from the atomization of acoustically levitated droplets

AA << report the dynamics of a droplet levitated in a single-axis acoustic levitator. The deformation and atomization behavior of the droplet in the acoustic field exhibits a myriad of complex phenomena, in sequences of steps. These include the primary breakup of the droplet through stable levitation, deformation, sheet formation, and equatorial atomization, followed by secondary breakup which could be umbrella breakup, bag breakup, bubble breakup or multistage breakup depending on the initial size of the droplet. >>

<< Both the primary and the secondary breakup of the droplet admit interfacial instabilities such as Faraday instability, Kelvin Helmholtz (KH) instability, RT instability, and RP instability and are well described with visual evidence. >>️

Sunil K. Saroj, Rochish M. Thaokar. Atomisation of an acoustically levitated droplet: Experimental observations of a myriad of complex phenomenon. arXiv: 2307.00400v1 [physics.flu-dyn]. Jul 1, 2023.

https://arxiv.org/abs/2307.00400

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

Keywords: gst, drop, droplet, transition, instability

# gst: laminar and turbulent flows detected in music, a fluid framework approach

<< The relationship between musical material and physical phenomena has become a topic in the musicological literature over the last several decades, particularly concerning elements of the musical system itself, and constructions found in the work of contemporary classical composers such as Gyorgy Ligeti and Iannis Xenakis. Most scholars, who adopt this approach, explore the physical phenomena of fractals in the analysis of musical works, but fluid mechanical frameworks, such as laminar and turbulent flows, offer a new avenue to be explored. In this paper (AA) will propose a novel method of musical analysis for examining musical structures in terms of fluid-like behaviour such that Ligeti etude no. 9 serves as a model, whereby the metaphors of laminar and turbulent flows take precedence. >>

Noah Chuipka. Musico-acoustic Depictions of Laminar and Turbulent Flows in Ligeti Piano Etude No. 9 and a Novel Method of Analysis. arXiv: 2306.10093v1 [cs.SD]. Jun 17, 2023. 

https://arxiv.org/abs/2306.10093

Also: music, jazz, turbulence, in https://www.inkgmr.net/kwrds.html

Keywords: gst, music, jazz, turbulence

# gst: even a single bubble can produce creative musical outcomes

<< Producing original and arranging existing musical outcomes is an art that takes years of learning and practice to master. Yet, despite the constant advances in the field of AI-powered musical creativity, production of quality musical outcomes remains a prerogative of the humans. Here we demonstrate that a single bubble in water can be used to produce creative musical outcomes, when it nonlinearly oscillates under an acoustic pressure signal that encodes a piece of classical music. >>️

Ivan S. Maksymov. Musical creativity enabled by nonlinear oscillations of a bubble in water. arXiv:2304.00822v1 [cs.SD]. Apr 3, 2023. 

https://arxiv.org/abs/2304.00822

keyword "bubble" in FonT

https://flashontrack.blogspot.com/search?q=bubble

Keywords: gst, ai, fluid dynamics, bubble, sound, music, audio processing

# gst: intentional defects to trap confined acoustic modes that are protected from perturbation

AA << has discovered how to exploit certain defects to protect confined energy in acoustics systems. Their experimental approach provides a versatile platform to create at-will defects for further theoretical validation and to improve control of waves in other systems, such as light >>

<< We set to understand whether topological defects, such as disclinations, can be created to trap highly confined acoustic modes that are protected from perturbation, (..) Our core insight was that, if we consider the point group symmetry of the disclination, a pair of disclinations modes are prevented from pairing away from zero frequency. This protection mechanism results from the interplay of the symmetry-protected topological phase of the crystalline lattice and the topological charge and symmetry of the disclination. >> Wladimir A. Benalcazar.

<< This is the first work experimentally validating that such protected states exist in the disclination core, >> Yun Jing. 

️

Ashley J. Wennersherron. Researchers find imperfections provide protection for system symmetry. Penn State College of Engineering. May 20, 2022.

https://phys.org/news/2022-05-imperfections-symmetry.html

Sarah Wells. Symmetrical Binding for Topological States. Physics 15, s56. Apr 26, 2022. 

https://physics.aps.org/articles/v15/s56

Yuanchen Deng, Wladimir A. Benalcazar, et al. Observation of Degenerate Zero-Energy Topological States at Disclinations in an Acoustic Lattice. Phys. Rev. Lett. 128, 174301. Apr 26, 2022. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.174301

Also

keyword 'acoustic' in FonT

https://flashontrack.blogspot.com/search?q=acoustic

Keywords: gst, acoustics, acoustic metamaterials, symmetry, system symmetry, imperfection, defect, topological defects, disclination

# astro: going beyond a performance by Frank Zappa (or a speech by – for example – a political entity), two speeds of sound found on Mars

AA << find that atmospheric sounds extend measurements of pressure variations down to 1,000 times smaller scales than ever observed before, revealing a dissipative regime extending over 5 orders of magnitude in energy. Using point sources of sound (Ingenuity rotorcraft, laser-induced sparks), (AA) highlight two distinct values for the speed of sound that are ~10 m/s apart below and above 240 Hz, a unique characteristic of low-pressure CO2-dominated atmosphere. (They) also provide the acoustic attenuation with distance above 2 kHz, allowing to elucidate the large contribution of the CO2 vibrational relaxation in the audible range. >>

Maurice, S., Chide, B., Murdoch, N. et al. In situ recording of Mars soundscape. Nature. doi: 10.1038/ s41586-022-04679-0. Apr 1, 2022. 

https://www.nature.com/articles/s41586-022-04679-0

<< All of these factors would make it difficult for two people to have a conversation only five meters (16 feet) apart >> Sylvestre Maurice.

Juliette Collen and Daniel Lawler. First audio recorded on Mars reveals two speeds of sound. Phys.org. Apr 1, 2022. 

https://phys.org/news/2022-04-audio-mars-reveals.html

NASA Perseverance Rover Captures 

Puff, Whir, Zap Sounds from Mars 

https://youtu.be/lX5iVyfF3N0

Also

Frank Zappa 

https://www.zappa.com/

image from  

https://www.zappa.com/sites/g/files/aaj776/f/styles/suzuki_breakpoints_image_tablet_16x9/public/news/202104/Zappa88-Home-banner-03.jpg

keywords: astro, mars, acoustics, sound, speed of sound, dissipative regimes, music, jazz, freejazz

# gst: apropos of discomfort tolerances, maximize a sweet spot (of a sound zone)

AA << considered the sweet spot as the region where the a sound scene is psycho-acoustically close to a desired auditory scene. >>

They << developed a method (SWEET-ReLU algorithm) that generates a sound scene that maximizes this sweet spot while guaranteeing no discomfort over a spatial region of interest. (..) the sweet spot and the discomfort tolerance can be modeled within a flexible monaural psycho-acoustic framework. >>

Pedro Izquierdo Lehmann, Rodrigo F. Cadiz, Carlos A. Sing Long. Maximizing the Psycho-Acoustic Sweet Spot. arXiv: 2201.01461v1 [eess.AS]. Jan 5, 2022.

https://arxiv.org/abs/2201.01461

Keywords: sound, psycho-acoustics, discomfort tolerance

# ecol: mycological jazz

<< "Mycological" draws conceptually from fungal networks in forests and their interactions. Inspired by the work of ecologist Suzanne Simard, author Michael Pollan, and mycologist Paul Stamets; Krolak saw many parallels between biological networks and the social network known as jazz, as well as, the acoustic networks created when musicians interact through their instruments. Aesthetically, the work is of the free and avant-garde traditions of jazz. Drawing inspiration from John Coltrane to Sonny Sharrock to Makaya McCraven, Krolak seeks to create a space for various elements to play out and find their own connections. >>

Mycological By Nicholas Krolak. All About Jazz. Jan 8, 2022. 

https://www.allaboutjazz.com/media/track-mycological-by-nicholas-krolak

Also

Apropos of 'mycological jazz', a old  perplexity of mine, who knows why substantial funds were no longer allocated to sci research on viruses, bacteria, fungi (..) and their ecological 'jazzy interactions' ... ? 😏

keyword 'virus' | 'bacteria' | 'fungi' in FonT

https://flashontrack.blogspot.com/search?q=virus

https://flashontrack.blogspot.com/search?q=bacteria

https://flashontrack.blogspot.com/search?q=fungi

Also

Much of intelligence (quasi-stochastic poetry). Notes. Dec 16, 2005.

https://inkpi.blogspot.com/2005/12/1929-much-of-intelligence.html

keyword 'jazz' in FonT

https://flashontrack.blogspot.com/search?q=jazz

keyword 'jazz' in Notes (quasi-stochastic poetry):

https://inkpi.blogspot.com/search?q=jazz

Keywords: jazz, viruses, bacteria, fungi, interactions, acad, scires, funds

# gst: contactless manipulation of droplets levitating in an acoustic wave

<< A unique, versatile, and material-independent approach to manipulate contactlessly and merge two chemically distinct droplets suspended in an acoustic levitator is reported. Large-amplitude axial oscillations are induced in the top droplet by low-frequency amplitude modulation of the ultrasonic carrier wave, which causes the top sample to merge with the sample in the pressure minimum below. The levitator is enclosed within a pressure-compatible process chamber to enable control of the environmental conditions. The merging technique permits precise control of the substances affecting the chemical reactions, the sample temperature, the volumes of the liquid reactants down to the picoliter range, and the mixing locations in space and time. >>

Stephen J. Brotton, Ralf I. Kaiser. 

Controlled Chemistry via Contactless Manipulation and Merging of Droplets in an Acoustic Levitator. Anal. Chem. 2020, 92, 12, 8371–8377. doi: 10.1021/ acs.analchem.0c00929. Jun 1, 2020. 

https://pubs.acs.org/doi/10.1021/acs.analchem.0c00929#

Levitating droplets allow scientists to perform 'touchless' chemical reactions.  American Chemical Society. Jun 24, 2020.

https://phys.org/news/2020-06-levitating-droplets-scientists-touchless-chemical.html  

# gst: the sounds that occur when a soap bubble pops.

<< The popping sound of a bursting soap bubble is acquired using microphone arrays and analyzed using spherical harmonics decomposition. >>

the << acoustic emission originates mainly from the capillary stresses exerted by the liquid soap film on the air and that it quantitatively reflects the out-of-equilibrium evolution of the flowing liquid film. (..) the acoustic signature of violent events of physical or biological origin could be used to measure the forces at play during these events. >>

Adrien Bussonniere, Arnaud Antkowiak, et al. Acoustic Sensing of Forces Driving Fast Capillary Flows. Phys. Rev. Lett. 124, 084502 Feb 27, 2020.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.084502

Bob Yirka. Measuring the sound of a soap bubble popping. Phys.org. Mar 2, 2020.

https://m.phys.org/news/2020-03-soap.html

# lang: information management (encoding reliability) in bird communications (among wild redbreasted nuthatches, Sitta canadensis)

<< Every social network has its fake news. And in animal communication networks, even birds discern the trustworthiness of their neighbors, >>

<< This is the first time people have shown that nuthatches are paying attention to the source of information, and that influences the signal they produce and send along, (..) Everybody is listening to everybody else in the woods, >> Erick Greene.

Courtney Brockman. Researchers study how birds retweet news. University of Montana. Feb 14, 2020. 

https://m.phys.org/news/2020-02-birds-retweet-news.html

<< nuthatches discriminate between direct and indirect, or public information, and this is reflected in the acoustic structure of their alarm calls. >>

Nora V Carlson, Erick Greene,  Christopher N Templeton. Nuthatches vary their alarm calls based upon the source of the eavesdropped signals. 

Nat Commun 11, 526. Jan 27, 2020.

https://www.nature.com/articles/s41467-020-14414-w

Also

the question is: Humans vs Woodstock, who is the smarter? Jun 26, 2016.

https://flashontrack.blogspot.com/2016/06/s-brain-question-is-humans-vs-parrots.html

keyword 'bird' in FonT

https://flashontrack.blogspot.com/search?q=bird

# chem: acoustic levitation techniques to perform chemistry in floating droplets

<<  Beauchamp (Jack Beauchamp) is doing work in what he calls "lab-in-a-drop" chemistry, in which chemical reactions are performed within a drop of liquid suspended in midair through acoustic levitation. >>

Performing chemistry in floating droplets. California Institute of Technology. Jul 29, 2019.

https://m.phys.org/news/2019-07-chemistry-droplets.html  

Chaonan Mu, Jie Wang, et al. Mass Spectrometric Study of Acoustically Levitated Droplets Illuminates Molecular‐Level Mechanism of Photodynamic Therapy for Cancer involving Lipid Oxidation. Angewandte Chemie International Edition. Volume 58, Issue 24. doi: 10.1002/anie.201902815. Apr 23, 2019.

https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201902815 

# behav: large-eared bats adopting slow-flight feeding strategies

AA << compare quantitative aerodynamic measures of flight efficiency of two bat species, one large-eared (Plecotus auritus) and one small-eared (Glossophaga soricina), flying freely in a wind tunnel >>

AA << find that the body drag of both species is higher than previously assumed and that the large-eared species has a higher body drag coefficient, but also produces relatively more ear/body lift than the small-eared species >>

<< The relatively higher power of the large-eared species results in lower optimal flight speeds and [AA] findings support the notion of a trade-off between the acoustic benefits of large external ears and aerodynamic performance. The result of this trade-off would be the eco-morphological correlation in bat flight, with large-eared bats generally adopting slow-flight feeding strategies >>

Jonas Hakansson, Lasse Jakobsen, et al. Body lift, drag and power are relatively higher in large-eared than in small-eared bat species. 2017; 14 (135): 4099. doi: 10.1098/rsif.2017.0455. Oct 25, 2017.

http://rsif.royalsocietypublishing.org/content/14/135/20170455

The pros and cons of large ears. Nov 10, 2017

http://www.lunduniversity.lu.se/article/the-pros-and-cons-of-large-ears

https://www.sciencedaily.com/releases/2017/11/171110084634.htm

# behav: even more devious than previously thought

<< The common cuckoo, notorious for evading parental duty by hiding her eggs in the nests of other brooding birds, is even more devious than previously thought >>

Scientists expose true extent of cuckoo's cunning. Sept 4, 2017

https://m.phys.org/news/2017-09-scientists-expose-true-extent-cuckoo.html

<< Parasites evolve not only to evade host defences but also to manipulate host behaviour >>

AA << test whether a brood parasitic cuckoo manipulates host perception of predation risk using an acoustic signal—a hawk-like call—that might misdirect host defences and thereby reduce the chance that hosts detect parasitism >>

AA << propose that the female cuckoo chuckle call tricks the hosts into responding vigilantly as if they were exposed to danger from a hawk, instead of from a cuckoo. This would divert host attention from clutch protection to self-protection, and so reduce the chance of the hosts detecting that they have been parasitized >>

Jenny E. York, Nicholas B. Davies. Female cuckoo calls misdirect host defences towards the wrong enemy. Nature Ecology & Evolution. Sept 4, 2017 doi: 10.1038/s41559-017-0279-3

https://www.nature.com/articles/s41559-017-0279-3

# phyto: feel sounds to spot water

AA << used the model plant Pisum sativum to investigate the mechanism by which roots sense and locate water >>

AA << found that roots were able to locate a water source by sensing the vibrations generated by water moving inside pipes, even in the absence of substrate moisture. When both moisture and acoustic cues were available, roots preferentially used moisture in the soil over acoustic vibrations, suggesting that acoustic gradients enable roots to broadly detect a water source at a distance, while moisture gradients help them to reach their target more accurately >>

AA << results also showed that the presence of noise affected the abilities of roots to perceive and respond correctly to the surrounding soundscape >>

Monica Gagliano, Mavra Grimonprez, et al. Tuned in: plant roots use sound to locate water. Oecologia. Volume 184, Issue 1, pp 151–160. May 2017

https://link.springer.com/article/10.1007%2Fs00442-017-3862-z

# s-phys: nanoquakes: driving them by phononic crystals

<< the extreme frequency sound waves - also known as surface acoustic waves [SAW] or 'nanoquakes' , as they run across the surface of a solid material in a similar manner to earthquake tremors on land >>

<< Although surface acoustic waves form a key component of a host of technologies, they have proved extremely difficult to control with any degree of accuracy >>

[AA] << have developed a new type of structure, known as a ' phononic crystal,' which when patterned into a device, can be used to steer and guide the nanoquakes >>

Riding the wave: Pioneering research tames nanoquakes. Aug 2, 2017

https://m.phys.org/news/2017-08-nanoquakes.html

<< Phononic crystals can control the propagation of SAW, analogous to photonic crystals, enabling components such as waveguides and cavities >>

B. J. Ash, S. R. Worsfold, et al. A highly attenuating and frequency tailorable annular hole phononic crystal for surface acoustic waves.  Nature Communications 8, Article number: 174 (2017)  doi:10.1038/s41467-017-00278-0

https://www.nature.com/articles/s41467-017-00278-0

# s-astro: the sonic multiverse, by Gavin Starks

<< A project that explores whether there is a musical equivalent to the curvature of spacetime will be presented on Thursday 6 July by Gavin Starks at the National Astronomy Meeting at the University of Hull >>

AA << aim is to test whether mathematical relationships that describe cosmology and quantum mechanics can be applied to a sonic universe , or 'soniverse' >>

Royal Astronomical Society. Adventures in acoustic cosmology. July 6, 2017

https://m.phys.org/news/2017-07-adventures-acoustic-cosmology.html

Gavin Starks. Escape into the multiverse. Jan. 27, 2017

http://www.binarydust.org/2017/01/27/escape-into-the-multiverse/