Dynamics and stability of gas-liquid foams

Gas-liquid foams are simple everyday materials which have a number of useful applications, particularly in cleaning and remediation. These gas-liquid foams are interesting materials to study in their own right, particularly when the foam has a low liquid fraction where the bubbles are crowded together, and the gas-liquid interfaces exhibit highly complicated geometries. However, these foams can also be used as a precursor to form other useful materials or to give insight into fundamental physical processes in crystalline materials.

For example, we are interested in using molten gas-liquid foams as a precursor to form high-porosity metallic solids for use as lightweight engineering materials. In particular, we use continuum mechanics and thermal modelling to study how a gas-liquid foam can be solidified, where the rapid changes in temperature and flow induced through the solidification front can interact with the foam structure. Our aim is to devise new experimental protocols where the molten foam can be frozen with its porous structure still intact, tailoring this final structure to have desirable physical properties such as strength and rigidity.

Furthermore, we are also interested in using these gas-liquid foams to gain insight into fundamental processes in the deformation of crystalline materials. It has long been established that gas-liquid foams form a useful microscale analogue of the crystalline structure of metals at the atomic level. By devising models for the motion of individual structural elements in the foam, we use discrete and continuum modelling approaches to quantify the role of these elements in plastic deformation of the material (such as ductile finger propagation) and during brittle foam fracture (see figure). Such models can then be used to inform new approaches for modelling plasticity and fracture in crystalline materials.