Measuring Fluid Interfaces, Corners, and Angles From High-Speed Digital Images of Impacting Drops

Biolè, D.; Bertola, Volfango

doi:10.1615/jflowvisimageproc.2020032697

Cited by 4 publications

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“…A digital image processing algorithm running in Matlab environment was used to extract quantitative information from high-speed videos of spreading droplets [26]. First, videos were pre-processed to enhance contrast by equalizing the intensity histogram, and to remove the background by subtracting pixel-by-pixel a reference image of the substrate from each frame of the captured videos:…”

Section: Methodsmentioning

confidence: 99%

The Onset and Early Stages of Dynamic Wetting of Superspreading and Non-Superspreading Trisiloxane Surfactant Solutions on Hydrophobic Surfaces

Bertola

2024

Colloids and Interfaces

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The onset and early stages of dynamic wetting on different hydrophobic surfaces is investigated experimentally for aqueous solutions of two commercial trisiloxane surfacants of similar chemical structure, one of which exhibits superspreading behaviour, in order to investigate the spreading dynamics independently of the surface activity. Superspreading, or the ability of a surfactant solution to spread on a surface beyond the state determined by thermodynamic equilibrium, has been investigated for more than 30 years however its physical mechanism remains poorly understood to date despite its important applications in the formulation of agrochemicals. Surfactant solutions were prepared by dissolving S233 and S240 surfactants (Evonik Industries AG, Essen, Germany) into de-ionised water at a weight concentration of 0.1%. Drops of surfactant solutions and pure water were deposited on three horizontal substrates with different wettability (equilibrium contact angle of water ranging between 55∘ and 100∘), and observed from below with a high-frame rate camera to visualise the advancing contact line. The spreading ratio of drops as a function of time was extracted from high-speed videos by digital image processing. Results reveal that the superspreading solution exhibits an intermittent spreading rate, as well as peculiar features of the contact line, which are not observed for the non-superspreading solution, and confirm the superspreading effect becomes less significant when the surface energy of the substrate is decreased.

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Section: Methodsmentioning

confidence: 99%