Laboratoire NAVIER, Equipe Rhéophysique - Laboratoire FAST, Equipe Granulaire et Suspension
F. Rouyer, Y. Khidas, V. Langlois, O. Pitois, X. Chateau - Georges Gauthier, Antoine Seguin
In this proposal, our objective is to study the physics of gas marbles.
In a ternary diagram (solid-liquid-gas), gas marbles share the domain of high gas, low solid and very low liquid fraction with already well-known three phase materials:
wet (unsaturated) granular materials, Pickering foams, granular foams. At the microscale of all these materials,
three physical mechanisms inducing (possibly multicore) interactions between grains are at play: capillarity,
grains contacts and viscous dissipation (in the liquid film and at the liquid/gas interfaces).
The time scales, length scales and patterns differs from one systems to another, as the particles and liquid network differ.
The main concern common to all dispersed media made of two or three phases are: How microstructure of the dispersed phases and microscale interactions are related and
affect the macroscale behavior of the material? Are all these systems one class of material in a sense that they obey the same constitutive laws
but with different state parameters defined by the physic at play at the microscale?
Studying gas marbles would help to give new inputs to these questions and propose a unified view to the subject.
To tackle these questions, we will carry out experiments at the different scales of the material
where the parameters of the continuous phase and dispersed phase will be controlled in order to reveal the main physical features of these new objects.
At the mesoscale, we want to understand the link between the particle network and the behavior of the gas marble membrane when subject to difference solicitations:
global and local forcing, vibrations and classical rheometry. In the quasi-static regime,
we will study the influence of the capillary pressure on the elasticity of the membrane and the granular network in terms of particle fraction, neighbor’s number,
aggregation coefficient. In the dynamic regime, the relevance of grains contact dissipation compare to the interfacial dissipation or liquid viscous dissipation will be address.
On the route to the macroscale, we have the first objective to create a gas marble with controlled properties, the second one is to correlate the static behavior
of one gas marble and a gas marbles assembly to the properties of the membrane and/or shell.
Finally, the dynamical properties of one gas marbles and gas marbles assembly will be studied by vibrational waves propagation and interpreted in regards to
the damping properties of the granular films and the network assembly of the gas marbles. The multi-scale and ternary structure of the material might reveal
different coupling modes of propagation (waves propagation in air and in the granular skeleton).
Figure 1: side view of a gas marble (particles diameter = 250 µm). b and c are sketches of the granular shell at the particle scale.