High-speed optical imaging of liquid film flow and liquid macro-slip over free surfaces with different surface energies

Polajnar, Marko (author), Bizjan, Benjamin (author), Širok, Brane (author), Kalin, Mitjan (author)

High-speed optical imaging is introduced as a visualization method to investigate the film-flow properties of liquids with different surface tensions and viscosities (water, poly-alpha-olefin oil, and glycerol) over free rotating surfaces with different surface energies and polarities (steel, and two different diamond-like-carbon - DLC coatings, i.e. DLC, and F-DLC). It was found that the polar surface energy strongly influences the structural dynamics of the liquid film's flow and the film's slip. Namely, a decrease in the polar surface energy results in a less stable filmwith de-wetting areas and breakups into streams, as well as in a larger amount of film slip, which was most clearly expressed by the F-DLC. It was also found that the combination of a high surface tension and a low viscosity provides the largest amount of liquid slip, with the most obvious breakup of the liquid film being observed with water, which clearly exhibits these properties.

• Language: English
• Keywords: high-speed optical imaging, liquid slip, surface energy, surface tension, viscosity
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Submitted Version
• Year: 2017
• Number of pages: f. 557-566
• Numbering: Vol. 29, iss. 8
• PID: 20.500.12556/RUL-106780
• UDC: 532(045)
• ISSN on article: 1557-6833
• DOI: 10.1002/ls.1388
• COBISS.SI-ID: 15511579
• Publication date in RUL: 18.03.2019

Secondary language

• Language: Slovenian
• Keywords: hitra kamera, zdrs v tekočinah, površinska energija, površinska napetost, viskoznost

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0231
• Name: Tribologija