The Bubble Films, Interference and Turbulences Under Microgravity and Gravity Conditions

Paper number

IAC-05-A2.1.05

Author

Ms. Agnieszka Wasylewicz, University of Gdansk, Poland

Coauthor

Mr. Wojciech Miloch, University of Oslo, Norway

Coauthor

Mr. Lukasz Redlarski, University of Gdansk, Poland

Coauthor

Mr. Adam Schroder, University of Gdansk, Poland

Year

2005

Abstract

Bubbles and soap films fascinate those who observe them. From the scientific point of view, the understanding of behaviour of such bubbles and films leads to important results in mathematics (minimum surface theory) and physics (surface tension forces, thin-film interference). Observation of the turbulent flows and transport in films is of the high importance in fluid dynamics with many applications as for example in material science and technology. 

In the bubble or the soap film, the thin layer of water is captured between two layers of soap molecules. The water layer is often in order of nanometers, and thus it is possible to observe interference patterns both in reflected and transmitted light, due to refraction and reflections of the light from different surfaces of the film. This phenomenon can be used to determine thickness of the film. 

Gravity force causes the change of thickness of the non-horizontal film in time. The liquid goes down and the thickness of the film is changing, which influences the observed interference pattern. Sudden disturbances in fluid flow can be a source for local turbulences, which are observed as a change of the interference pattern. Finally, the film or the bubble is destroyed. In the horizontal films, the gravity force creates the cavity, which also leads to the changes in the interference pattern.

Under microgravity condition, soap films and bubbles are much more stabile, and their shapes are almost "ideal", according to the theory. Therefore, it is much easier to analyze the surface tension forces for different films and frames materials. 

To investigate the film behaviour and interference patterns in the absence of gravity, the group of four students designed the experiment for the Student Parabolic Flight Campaign (which can be also done on the drop tower). In the experiment, different soap films on frames of different thickness and materials are examined. We obtain the minimal thickness of the film by enlarging its area. While being enlarged, the film is illuminated with a monochromatic light (e.q. sodium lamp), and the thickness is measured using the interference patterns.  To observe the turbulences and transport of liquid we inject coloured water into the stabile films. The interference patterns and the transport in the film are recorded with the camera. 

The paper presents the set-up, execution and results of the experiment together with the theory based discussion. The data from the microgravity conditions are compared with the relevant data under the gravity and hyper-gravity conditions. 

Abstract document

IAC-05-A2.1.05.pdf

Manuscript document

IAC-05-A2.1.05.pdf (🔒 authorized access only).

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