2009/04/02 by Jacobus A. van Meel, van Meel, Jacobus A., Harald A. Posch +1
Engineering · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Astro and Planetary Science #Chaotic Dynamics (nlin.CD) #FOS: Physical sciences #Phase Equilibria and Thermodynamics #nlin.CD
paper · pdf · doi:10.48550/arxiv.0904.0357
11 pages, 8 figures, submitted to Physical Review E
arxiv created 2009/04/02 · openalex publication_date 2009/04/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The dynamical instability of rough hard-disk fluids in two dimensions is characterized through the Lyapunov spectrum and the Kolmogorov-Sinai entropy, hKS, for a wide range of densities and moments of inertia I. For small I the spectrum separates into translation-dominated and rotation-dominated parts. With increasing I the rotation-dominated part is gradually filled in at the expense of translation, until such a separation becomes meaningless. At any density, the rate of phase-space mixing, given by hKS, becomes less and less effective the more the rotation affects the dynamics. However, the degree of dynamical chaos, measured by the maximum Lyapunov exponent, is only enhanced by the rotational degrees of freedom for high-density gases, but is diminished for lower densities. Surprisingly, no traces of Lyapunov modes were found in the spectrum for larger moments of inertia. The spatial localization of the perturbation vector associated with the maximum exponent however persists for any I.