# gst: apropos of instability, bubbles may have unexpected chills

<< Bubbles are ubiquitous, existing in everything from the foam on a beer to party toys for children. Despite this pervasiveness, there are open questions on the behavior of bubbles, such as why some bubbles are more resistant to bursting than others. >>️

AA << created a soap bubble from a mixture made of dishwashing liquid, water, and glycerol. They then measured the soap film’s temperature under a variety of environmental conditions. They found that the film could be up to 8 °C colder than the surrounding air. They also found that glycerol content of the soap film impacted this temperature difference, with films containing more glycerol having higher temperatures. Boulogne (Francois Boulogne) says that such a large temperature difference could impact bubble stability.  >>️

Anna Napolitano. Bubbles Have an Unexpected Chill. Physics 15, s173. Dec 19, 2022. 

https://physics.aps.org/articles/v15/s173

Francois Boulogne, Frederic Restagno, Emmanuelle Rio. Measurement of the Temperature Decrease in Evaporating Soap Films. Phys. Rev. Lett. 129, 268001. Dec 19, 2022.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.268001

Also

keyword "bubble" in FonT

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

keyword "bolla" | "bolle" in Notes (quasistochastic-poetry): 

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

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

Keywords: gst, bubble, stability, evaporation, burst

# gst: transitional dynamics among gyrotactic (prolate spheroid) swimmers in turbulence

<< In this study, (AA) consider small, elongated, gyrotactic, swimming particles in homogenous isotropic turbulence (..). Many motile phytoplankton species are gyrotactic, i.e., their swimming direction results from the competition between shear-induced viscous torque and the stabilizing torque due to bottom-heaviness. (..)  Moreover, both single phytoplankton cells and multicellular phytoplankton chains can have elongated shapes, which makes the study of gyrotactic active particles with prolate shapes necessary. >>

AA addressed the following problems:

<< (i) How the clustering is affected by the swimming number Φ and the stability number Ψ? In particular, how to characterize the extent of clustering based on the three-dimensional Voronoi analysis?

(ii) How the clustering is related to the flow structures? This question has two perspectives.  From the space perspective, what are the regions that particles accumulate in? From the time perspective, how long do particles exist in an aggregated state? >>

Zehua Liu, Linfeng Jiang, Chao Sun. Accumulation and alignment of elongated gyrotactic swimmers in turbulence. arXiv:2202.04351v1 [physics.flu-dyn]. Feb 9, 2022.

https://arxiv.org/abs/2202.04351

Also

The effect of noise on the dynamics of microswimmers in externally-driven fluid flows.  

https://flashontrack.blogspot.com/2021/10/gst-effect-of-noise-on-dynamics-of.html

keywords 'turbulence' in FonT   

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

keywords 'turbolento' in Notes (quasi-stochastic poetry)

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

keywords: transition, swimmers,  gyrotactic swimmers, spheroids,  prolate spheroids, stability, turbulence

# gst: predict stability in a collapsing ring

<< it is possible to predict the stability of a collapsing ring by counting its kinks. (..) (AA) group describes experiments they conducted that involved placing an elastic ring over a soap film and recording what happens when the ring collapses. >>

Bob Yirka. Counting kinks in a collapsing ring to predict stability. May 20, 2020.

https://phys.org/news/2020-05-kinks-collapsing-stability.html   

Finn Box, Ousmane Kodio, et al. Dynamic Buckling of an Elastic Ring in a Soap Film. Phys. Rev. Lett. 124, 198003. 13 May 13, 2020.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.198003   

https://arxiv.org/abs/1812.11009