(291f) A Heart of Glass? Investigating the Spatiotemporal Correlation of Granular Dynamics in 3D Vibrated Beds

Granular materials exhibit a wealth of phenomena at the crossroads of the classical states of matter.¹ Indeed, when a vibrated granular material is increasingly compressed, the gas-like state condenses and forms a disordered solid once a critical solid fraction is reached. Previous experimental studies using tracking techniques observed precursors of a glass transition at this stage.^2,3 However, these studies were limited to two-dimensional systems and thus the nature of this transition in three-dimensional vibrated granular matter remains elusive.

Recently, we have developed a novel technique based on nuclear magnetic resonance that is capable of tracking the motion of many particles in three-dimensional granular systems (MRPT).⁴ In this work, we deploy the high spatiotemporal resolution of MRPT to investigate the dynamics of granular materials in continuously vibrated, three-dimensional beds. We study the effect of vibration strength, solid fraction and polydispersity of granular materials on their microstructural relaxation.

Analyzing the probability density function of the particle displacement, we observe Gaussian distributions for low solid fractions as particles perform random walks. However, when increasing the solid fraction, exponential tails emerge indicating the presence of spatially heterogeneous dynamics⁵, i.e. the co-existence of regions with high and low mobility. In addition, we investigate the shape and evolution of the radial distribution function of the particle bed and find a splitting of the second peak as well as a short-term structural memory. Both features indicate that three-dimensional vibrated granular beds share fundamental commonalities with other disordered glass-forming systems such as colloids⁶ and supercooled liquids⁷ although on very different temporal and spatial scales.

References

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3. Watanabe K, Tanaka H. Direct Observation of Medium-Range Crystalline Order in Granular Liquids Near the Glass Transition. Phys Rev Lett. 2008;100(15):158002.
4. Suter M, Metzger JP, Port A, Müller CR, Pruessmann KP. Magnetic Resonance Particle Tracking. arXiv:2503.22425. 2025.
5. Chaudhuri P, Berthier L, Kob W. Universal nature of particle displacements close to glass and jamming transitions. Phys Rev Lett. 2007;99(6).
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