Dynamics of laser-induced cavitation bubble during expansion over sharp-edge geometry submerged in liquid – an inside view by diffuse illumination

Senegačnik, Matej (author), Kunimoto, Kohei (author), Yamaguchi, Satoshi (author), Kimura, Koki (author), Sakka, Tetsuo (author), Gregorčič, Peter (author)

Laser ablation in liquids is growing in popularity for various applications including nanoparticle production, breakdown spectroscopy, and surface functionalization. When laser pulse ablates the solid target submerged in liquid, a cavitation bubble develops. In case of “finite” geometries of ablated solids, liquid dynamical phenomena can occur inside the bubble when the bubble overflows the surface edge. To observe this dynamics, we use diffuse illumination of a flashlamp in combination with a high-speed videography by exposure times down to 250 ns. The developed theoretical modelling and its comparison with the experimental observations clearly prove that this approach widens the observable area inside the bubble. We thereby use it to study the dynamics of laser-induced cavitation bubble during its expansion over a sharp-edge (“cliff-like” 90°) geometry submerged in water, ethanol, and polyethylene glycol 300. The samples are 17 mm wide stainless steel plates with thickness in the range of 0.025–2 mm. Bubbles are induced on the samples by 1064-nm laser pulses with pulse durations of 7–60 ns and pulse energies of 10–55 mJ. We observe formation of a fixed-type secondary cavity behind the edge where low-pressure area develops due to bubble-driven flow of the liquid. This occurs when the velocity of liquid overflow exceeds ~20 m s$^{−1}$. A re-entrant liquid injection with up to ~40 m s$^{−1}$ velocity may occur inside the bubble when the bubble overflows the edge of the sample. Formation and characteristics of the jet evidently depend on the relation between the breakdown-edge offset and the bubble energy, as well as the properties of the surrounding liquid. Higher viscosity of the liquid prevents the generation of the jet.

• Language: English
• Keywords: laser ablation in liquids, cavitation, bubble shadowgraphy, cavitation bubble, illumination, shadowgraphy, nanoparticle production, re-entrant jet
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 16 str.
• Numbering: Vol. 73, art. 105460
• PID: 20.500.12556/RUL-125585
• UDC: 532.528:681.7.069.24(045)
• ISSN on article: 1350-4177
• DOI: 10.1016/j.ultsonch.2021.105460
• COBISS.SI-ID: 46704131
• Publication date in RUL: 26.03.2021

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 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: laserska ablacija v kapljevinah, kavitacijski mehurček, senčna fotografija, osvetlitev, proizvodnja nanodelcev, vstopni curek