# gst: apropos of bubbles, the case of bubbles collapsing near a wall.

AA << study examines the pressure exerted by a cavitation bubble collapsing near a rigid wall. A laser-generated bubble in a water basin undergoes growth, collapse, second growth, and final collapse. Shock waves and liquid jets from non-spherical collapses are influenced by the stand-off ratio γ, defined as the bubble centroid distance from the wall divided by the bubble radius. (AA) detail shock mechanisms, such as tip or torus collapse, for various γ values. High-speed and Schlieren imaging visualize the microjet and shock waves. The microjet's evolution is tracked for large γ, while shock waves are captured in composite images showing multiple shock positions. Quantitative analyses of the microjet interface, shock wave velocities, and impact times are reported. Wall-mounted sensors and a needle hydrophone measure pressure and compare with high-speed observations to assess the dominant contributions to pressure changes with γ, revealing implications for cavitation erosion mechanisms. >>️

Roshan Kumar Subramanian, Zhidian Yang, et al. Bubble collapse near a wall. Part 1: An experimental study on the impact of shock waves and microjet on the wall pressure. arXiv: 2408.03479v2 [physics.flu-dyn]. Aug 8, 2024. 

https://arxiv.org/abs/2408.03479

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

Keywords: gst, bubble, bubble collapse 

# gst: approaching the dynamics of nanobubble formation and collapse

<< While sequential optical imaging (i.e., recording movies) has contributed significantly to our understanding of cavitation and other complex bubble behavior at the larger (..) scale, the necessary length and temporal resolutions make such a traditional approach infeasible for nanobubbles, >> Garth Egan. ️

<< To take the images at the nanoscale, (AA) shot a 532-nanometer laser pulse (about 12 nanosec) to excite gold nanoparticles inside a 1.2 micron layer of water. The resulting bubbles were observed with a series of nine electron pulses (10 ns) separated by as little as 40 ns peak-to-peak. The researchers found that isolated nanobubbles were observed to collapse in less than 50 ns, while larger (∼2–3 micron) bubbles were observed to grow and collapse in less than 200 ns. >>

<< Isolated bubbles were observed to behave consistently with models derived from data from much larger bubbles. The formation and collapse were observed to be temporally asymmetric, which has implications for how results from alternate methods of experimental analysis are interpreted. More complex interactions between adjacent bubbles also were observed, which led to bubbles living longer than expected and rebounding upon collapse. >>️️

Anne M. Stark. Multiframe imaging of micron and nanoscale bubble dynamics.  Lawrence Livermore National Laboratory. Feb 09, 2022. 

https://phys.org/news/2022-02-multiframe-imaging-micron-nanoscale-dynamics.html

Garth C. Egan, Edmond Y. Lau, Eric Schwegler.  Multiframe Imaging of Micron and Nanoscale Bubble Dynamics. Nano Lett. 2022, 22, 3, 1053–1058. doi: 10.1021/ acs.nanolett.1c04101. Jan 19, 2022.

https://pubs.acs.org/doi/10.1021/acs.nanolett.1c04101

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: bubble, nano, nanobubble,  nanobubble dynamics, bubble formation, bubble collapse