DROPLET DETACHMENT · Droplet detachment by thermal fluctuations
6РП — Действия „Мария Кюри“
- Период
- 2005-11-01 → 2006-11-30
- Финансиране от ЕС
- 88 191 €
- Участници
- 1
- Схема
- EIF
Линиите свързват координатора с партньорите.
Накратко на български
Термичните флуктуации влияят върху начина, по който се отделят микроскопични капки течност с много ниско повърхностно напрежение. Това помага за по-доброто разбиране на хидродинамиката в микро- и наномащаб, както и на процесите при мокренето на повърхности.
Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.
Резултати накратко
Final Activity Report Summary - DROPLET DETACHMENT (Droplet detachment by thermal fluctuations)
We have presented experimental evidence that drop breakup is caused by thermal noise in a system with a surface tension that is more than a million times smaller than that of water. We have observed that at very small scales classical hydrodynamics breaks down and the characteristic signatures of pinch-off due to thermal noise are observed. Surprisingly, the noise makes the drop size distribution more uniform, by suppressing the formation of satellite droplets of the smallest sizes. The crossover between deterministic hydrodynamic motion and stochastic thermally driven motion has repercussions for our understanding of small-scale hydrodynamics, important in many problems such as micro- or nanofluidics and interfacial singularities. This was the main goal of the Marie Curie EIF. Furthermore, we have studied and analysed the effects of shear on the thermal fluctuations in a system similar to the one used in the above work. Strikingly, we found that the shear strongly suppresses capillary waves, making the interface smoother. This phenomenon can be described by introducing an effective interfacial tension that increases with the shear rate. These observations are of fundamental importance. Finally, we have studied and analysed the influence of thermal fluctuations on the thickness of wetting layers. Here, we have demonstrated for the first time the importance of fluctuations in a system showing complete wetting with short ranged forces.
Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз
Цел на проекта
The process of droplet snap-off -as occurring in a dripping faucet- is frequently observed in daily life and includes rich and beautiful phenomena. As the radius of the neck decreases a singularity develops due to the infinite curvature at the point of snap-off. Both just before and after the point of snap-off molecular scales are reached.At such small scales thermal fluctuations start playing a role and this thermal noise greatly influences the observed behaviour as predicted by theory and simulations. Experiments that reach this scale are still lacking and here we propose to investigate droplet detachment affected by thermal fluctuations.As our model system we will use a fluid-fluid phase separating colloid-polymer mixture, which is well known to display behaviour analogous to molecular fluid-fluid systems. Given the current trend of miniaturization (see, for example, the field of microfluidics) this work is not only motivated from a fundamental point of view, but has clear technological relevance as well. In addition, a better understanding of droplet detachment may lead to a better control of spraying and other droplet formation methods, which are important industrial processes.Recently, we have been able to directly visualize thermal capillary waves in our model system by using an advanced microscopy technique. This observation can be considered as an important first step to address the effects of thermal noise in many different fundamental as well as technological issues. Here, we propose to explore the effects in droplet snap-off, which combines the expertise of the co-ordinator and that of the host.
Оригинален текст от CORDIS (на английски).
Участници
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE · PARISКоординаторФранция
Връзки
Данни: CORDIS, © Европейски съюз