#### Title

Strong Dynamical Heterogeneity and Universal Scaling in Driven Granular Fluids

#### Publication Date

2014

#### Journal

Physical Review Letters

#### Volume

113

#### Issue

2

#### First Page

5701

#### Last Page

5701

#### Abstract

Large-scale simulations of two-dimensional bidisperse granular fluids allow us to determine spatial correlations of slow particles via the four-point structure factor S-4 (q, t). Both cases, elastic (epsilon = 1) and inelastic (epsilon < 1) collisions, are studied. As the fluid approaches structural arrest, i.e., for packing fractions in the range 0.6 <= phi <= 0.805, scaling is shown to hold: S-4 (q, t)/chi(4)(t) = s(q xi(t)). Both the dynamic susceptibility chi(4)(tau(alpha)) and the dynamic correlation length xi(tau(alpha)) evaluated at the alpha relaxation time tau(alpha) can be fitted to a power law divergence at a critical packing fraction. The measured xi(tau(alpha)) widely exceeds the largest one previously observed for three-dimensional (3d) hard sphere fluids. The number of particles in a slow cluster and the correlation length are related by a robust power law, chi(4)(tau(alpha)) approximate to xi(d-p) (tau(alpha)), with an exponent d - p approximate to 1.6. This scaling is remarkably independent of epsilon, even though the strength of the dynamical heterogeneity at constant volume fraction depends strongly on epsilon.

#### Link to Published Version

http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.113.025701

#### Recommended Citation

Avila, Karina E.; Castillo, Horacio E.; Fiege, Andrea; Vollmayr-Lee, Katharina; and Zippelius, Annette. "Strong Dynamical Heterogeneity and Universal Scaling in Driven Granular Fluids." *Physical Review Letters* 113, no. 2 (2014)
: 5701-5701.

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