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Axisymmetric bare freestanding films of highly viscous liquids: Preparation and real-time investigation of capillary leveling
- Publication Year :
- 2021
-
Abstract
- Hypothesis Thin liquid films are important in many scientific fields. In particular, films with both the surface layers exposed to a different fluid phase, known as freestanding films, are relevant in the ambit of foams and emulsions. Hence, there is a great interest in developing novel techniques allowing to form large and stable freestanding liquid films and to follow their dynamics. Experiments We develop a novel opto-mechanical tool allowing to perform and study the preparation and the capillary leveling flow of axisymmetric bare freestanding liquid films. The tool is composed by a customized motorized iris diaphragm and by an innovative joint imaging setup combining digital holography and white light color interferometry that enables real-time measurement of film thickness over a large field of view. The dynamics of films made of a model Newtonian fluid, i.e., high-viscosity silicone oil, is studied. Direct numerical simulations and a hydrodynamic model based on the lubrication theory are used to support the experimental results. Findings Iris opening induces the formation of large circular freestanding films with a stepped profile. Once iris opening is stopped, the films undergo a capillary leveling flow tending to flatten their profile. The leveling flow follows the theoretical scaling given by Ilton et al. [1]. We prove through numerical simulations that an equi-biaxial extensional flow occurs at the film center. Furthermore, we observe the formation and dynamics of dimples in bare freestanding films for the first time.
- Subjects :
- Materials science
Capillary action
Flow (psychology)
Rotational symmetry
02 engineering and technology
Viscous liquid
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
Lubrication theory
0104 chemical sciences
Surfaces, Coatings and Films
Electronic, Optical and Magnetic Materials
Biomaterials
Colloid and Surface Chemistry
Axisymmetric bare freestanding liquid film
Dimple
Newtonian fluid
Composite material
0210 nano-technology
Capillary leveling flow
Opto-mechanical device
Digital holography
Direct numerical simulation
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....614ace4cef5301ac63b9c2cfae303dcc