Laser-induced shock-wave-expanded nanobubbles in spherical geometry

Horvat, Darja (author), Agrež, Vid (author), Požar, Tomaž (author), Starman, Bojan (author), Halilovič, Miroslav (author), Petkovšek, Rok (author)

The secondary cavitation generation following laser-induced breakdown in aqueous media in spherical geometry, mimicking the geometry of the frontal part of the human eye, was studied. A numerical simulation of the shock wave propagation was performed, yielding peak-pressure maps, correctly predicting the location of the secondary cavitation onset for different shock wave source positions. The comparison between the simulation results and the experiments, performed with a high-precision, multiple-illumination technique, supports the suggested description of the nature of the secondary cavitation onset. It is shown that large transient negative pressures are created at the location of the acoustic image of the shock wave source, which is different from the optical focus. After the passage of the shock wave, abundant secondary cavitation is generated there. Additionally, the existence of an important contributing factor to the reduction of the secondary cavitation threshold is supported by the experimental results, namely the pre-illumination of the water by the breakdown-generating laser pulse, playing a crucial role in conditioning the medium. There is strong experimental evidence of the existence of another mechanism of pre-conditioning the water for the secondary cavitation onset, namely in the form of repetitive negative pressure pulse passage through the same volume, an indication of a possible two- or multiple-stage process.

• Language: English
• Keywords: shock wave, cavitation bubbles, secondary cavitation, pre-illumination, cavitation, bubble
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 12 str.
• Numbering: Vol. 89, art. 106160
• PID: 20.500.12556/RUL-140844
• UDC: 532.528
• ISSN on article: 1350-4177
• DOI: 10.1016/j.ultsonch.2022.106160
• COBISS.SI-ID: 122021123
• Publication date in RUL: 20.09.2022

Record is a part of a journal

• Title: Ultrasonics Sonochemistry
• Shortened title: Ultrason. sonochem.
• Publisher: Butterworth-Heinemann, Elsevier Science
• ISSN: 1350-4177
• COBISS.SI-ID: 707668

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: udarni val, kavitacijski mehurčki, sekundarna kavitacija, predosvetlitev