Intermediate regimes in granular Brownian motion: Superdiffusion and subdiffusion

Anna Bodrova, Awadhesh Kumar Dubey, Sanjay Puri, Nikolai Brilliantov

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26 Citations (Scopus)


Brownian motion in a granular gas in a homogeneous cooling state is studied theoretically and by means of molecular dynamics. We use the simplest first-principles model for the impact-velocity dependent restitution coefficient, as it follows for the model of viscoelastic spheres. We reveal that for a wide range of initial conditions the ratio of granular temperatures of Brownian and bath particles demonstrates complicated nonmonotonic behavior, which results in a transition between different regimes of Brownian dynamics: It starts from the ballistic motion, switches later to a superballistic one, and turns at still later times into subdiffusion; eventually normal diffusion is achieved. Our theory agrees very well with the molecular dynamics results, although extreme computational costs prevented us from detecting the final diffusion regime. Qualitatively, the reported intermediate diffusion regimes are generic for granular gases with any realistic dependence of the restitution coefficient on the impact velocity.

Original languageEnglish
Article number178001
JournalPhysical Review Letters
Issue number17
Publication statusPublished - 23 Oct 2012
Externally publishedYes


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