Collective activity of air-fluidized granular pentagons

Extending the understanding of amorphous matter from idealized particle systems to real-world materials can be challenging due to the complexity of particle interactions. We study the collective behaviors of pentagon-shaped granular particles with many-body interactions. Experimentally, we induce an uplifting airflow to fluidize a two-dimensional particle layer, resulting in quasi-thermal motion for individual particles. The particle geometry can then be manipulated to induce an aerodynamic attraction among particles with many-body effects. In a large and quiescent system without external loading, the measured particle mean-squared displacement indicates that the particles can be super-diffusive, making these particles effectively active. The super-diffusivity is accompanied by large and correlated particle displacements that tend to occur in dense regions with structural disorder. We compare experimental results with molecular dynamics simulations of active pentagon-shaped particles that follow Langevin dynamics to understand how many-body effects result in the observed anomalous transport.