Flow dynamics in cavitation induced micro pumping

Agrež, Vid (author), Zevnik, Jure (author), Lokar, Žiga (author), Dular, Matevž (author), Petkovšek, Rok (author)

The micro pumping process driven by the laser induced cavitation bubbles is scalable, requires only optical access and does not require mechanical moving parts. We investigate how the positioning of the cavitation bubble affects the flow dynamics through differently sized holes in a transparent boundary mimicking a microchannel. For normalized standoff distance above 0.8 and normalized hole radius of 0.22 a significant flow through a hole was observed while decreasing the standoff distance a focused reverse flow was formed impeding downward pumping flow. The details of reverse flow formation were investigated. It was found that bubbles generated next to larger holes with a normalized radius of 0.66 also produce reverse flow, however without it impeding the flow through the structure, even at small normalized standoff distances. Simulations were found to agree well with experiments and used to further study the pumping behavior. Indentation on the bottom side of the bubble was found to be the driver of the focused reverse flow in simulations and differences were investigated for various hole radii and standoff distances. For larger hole radii, reverse flow was found to be both weaker and failed to block the entire hole width, permitting pumping behavior. To improve the flow in the pumping direction, additional structures were produced on top of the flat plate with holes. It was found that adding the entry structure to the hole mitigated the effect of the focused reverse flow on the pumping action.

• Language: English
• Keywords: cavitation, reverse flow, micro channel, micro pumping, rigid boundary, counter 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: 2025
• Number of pages: 13 str.
• Numbering: Vol. 169, art. 111540
• PID: 20.500.12556/RUL-169783
• UDC: 621
• ISSN on article: 1879-2286
• DOI: 10.1016/j.expthermflusci.2025.111540
• COBISS.SI-ID: 238977027
• Publication date in RUL: 11.06.2025

Record is a part of a journal

• Title: Experimental thermal and fluid science
• Shortened title: Exp. therm. fluid sci.
• Publisher: Elsevier
• ISSN: 1879-2286
• COBISS.SI-ID: 23399685

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: kavitacija, povratni tok, mikro kanal, mikro črpanje, trdna meja, povratni curek