New simulations link unusual particle diffusion to yielding in soft jammed matter
Soft materials such as colloidal suspensions, emulsions, foams and gels often display complex and unusual behaviors compared with ordinary solids or liquids. From a mechanical point of view, for instance, they can resist deformation like solids, but they can also start to flow like liquids when a sufficiently strong external drive is applied. This transition from solid-like to liquid-like…
New computer simulations have uncovered a link between the unusual diffusion of particles in soft, jammed materials and the point at which these materials begin to yield under stress. Such materials, like colloidal suspensions, foams and gels, exhibit both solid-like and liquid-like properties and their behavior is influenced by both mechanical forces and interactions with neighboring particles.
The study, conducted at the University of Naples Federico II, demonstrates that a specific type of diffusion called Fickian non-Gaussian diffusion (FnGD) can emerge in these materials even when they are not exposed to thermal energy. FnGD, which combines a linear increase in displacement over time with a non-Gaussian distribution of particle movements, is typically found in systems with active particle dynamics.
However, the research shows that this type of diffusion can also occur in athermal materials, where thermal motion is negligible. The team found that FnGD is closely tied to the onset of yielding in soft materials, suggesting that this microscopic behavior may have a significant impact on the macroscopic properties of these systems.
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