Acoustic Probe for Liquid Foams – SAMOUSSE

Because of their original properties, liquid foams have become the subject of intense fundamental studies over the last 30 years. Rapid progress has been made on questions concerning foam structure, stability, drainage and rheology. Many of these studies reveal the importance of the physico-chemical composition of the foam. This is particularly true concerning the dynamical properties of foams where the nature of the stabilising agents confers two-dimensional visco-elastic properties to the gas/liquid interfaces. These are coupled to the flow of liquid within the foam skeleton, rendering the foam mechanical behaviour very complex. Trying to establish the link between the physico-chemical composition of foams and their dynamic properties is currently a very active research area in the international community.
Industrial applications of liquid foams have traditionally been very important and numerous, spanning a vast range of domains from food products to oil recovery. And most solid foams, of which millions of tons are produced every year, are made from liquid precursor foams. With an increasing understanding and control over the physical and physico-chemical properties of liquid foams many traditional applications experience a profound overhaul towards optimised performance and a large number of new types of foams are making their way into applications. Examples include important medical or military defence applications.
The resulting needs lead industrials to look for new tools to efficiently control and analyse those products, ideally in-situ during generation. The currently existing techniques do not satisfy all the needs, and most of all tend to be too slow.
Industry and academia is therefore experiencing a growing need for new versatile and fast techniques to probe liquid foams. For these reasons, the SAMOUSSE project aims to develop an acoustic probe for liquid foams, developing in parallel the fundamental scientific concepts and the acoustic technology. Acoustic techniques offer many advantages for the characterisation of materials since they provide a multitude of information whilst being rapid, transportable, inexpensive and non-destructive. Acoustic probes for certain diphasic media, such as emulsions, are already widely used. However, contrary to the case of emulsions, the acoustic properties of liquid foams are still ill-known. Some reports in the literature and the previous experience of the authors of this project on the acoustics of liquid foams provide very promising prospects for the development of such a probe. A detailed fundamental study remains necessary, and is an important part of this project.
The SAMOUSSE project is ambitious and needs to bring together skills in many diverse domains including the generation and analysis of liquid foams, interfacial rheology and acoustics of multiphasic media. These skills are present in the three academic laboratories involved in the project. The fourth partner, TECLIS, is an industrial partner who is currently providing instrumentation for the characterisation of liquid foams for an increasingly growing market. This consortium of academic and industrial partners will guarantee the success of the scientific and technological transfer from academia to industry, and the industrial development of the probe.
The SAMOUSSE project comes at a favourable moment with respect to the growing needs for foam characterisation tools, but also with respect to the central fundamental question of the dynamical properties of foams, which are still ill-known at high frequencies and are the subject of an intense international research activity. The acoustic provides a privileged angle to tackle this question. A funding via the ANR would solidly unite the consortium by providing the means to conduct the first exhaustive fundamental studies on acoustic properties of liquid foams, and to apply the obtained insight to the development of the first prototype of an acoustic probe.