Today, no one knows how to predict the lifespan of a foam. This seemingly simple problem conceals a complex reality, linked to the particular organisation of the liquid and gas in this material: films of soap of micrometric thickness separate bubbles of gas, and these films join together along thicker menisci.
"To make progress, we will need to measure two things very precisely: the velocity fields at the two interfaces of the film, and its thickness at a large number of points," says Isabelle Cantat.
"Simplified numerical models will be developed in parallel with the experiments. This will allow us to check whether the results of the simulations are in line with reality, and thus to test theoretical hypotheses. Hopefully, we will be able to identify the physical phenomena that play the most important roles in the problem. Not to mention the satisfaction of having elucidated at least part of the problem, we will then be able to pass on our results to our digital colleagues to develop more complete 3D models," says Isabelle Cantat.
The creation of a dedicated team, with the support of ERC funds
In addition to the purchase of the specific cameras needed, the ERC funds will finance a teaching release for Isabelle Cantat over five years, as well as the salaries of two full-time researchers (PhD students and post-docs). Part of the budget will also be used to participate in and organise conferences.
Foams are used in a wide range of fields. Food and cosmetics come to mind, but foams are also indispensable in oil and mining. The military also uses them to dampen the shock waves generated by explosions during mine clearance.
Once the mechanisms behind foam's stability and mechanical strength are well understood, it will be much easier to improve its properties.
"Imagine, for example, that you are a manufacturer of a household product that uses a surfactant to obtain a specific foam quality," explains Isabelle Cantat. "One day, however, it is discovered that this surfactant poses a risk to the environment and to health. So you have to change it very quickly. Well, our results will make it possible to define very precisely the properties of the new surfactant to be used to produce the desired foam, which will save a considerable amount of time compared to the trial and error methods used today."