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サイトウ クニヤス
Kuniyasu Saitoh
齊藤 国靖 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 発行・発表の年月 | 2019 |
| 形態種別 | その他 |
| 標題 | Rotational sound in disordered granular materials |
| 執筆形態 | その他 |
| 掲載誌名 | Physical Review E |
| 巻・号・頁 | 99(1) |
| 著者・共著者 | Saitoh, K.,Shrivastava, R.K.,Luding, S. |
| 概要 | We employ numerical simulations to understand the evolution of elastic<br />
standing waves in disordered frictional disk systems, where the dispersion<br /> relations of rotational sound modes are analyzed in detail. As in the case of<br /> frictional particles on a lattice, the rotational modes exhibit an<br /> "optical-like" dispersion relation in the high frequency regime, representing a<br /> shoulder of the vibrational density of states and fast oscillations of the<br /> autocorrelations of rotational velocities. A lattice-based model describes the<br /> dispersion relations of the rotational modes for small wave numbers. The<br /> rotational modes are perfectly explained by the model if tangential elastic<br /> forces between the disks in contact are large enough. If the tangential forces<br /> are comparable with or smaller than normal forces, the model fails for short<br /> wave lengths. However, the dispersion relation of the rotational modes then<br /> follows the model prediction for transverse modes, implying that the fast<br /> oscillations of disks' rotations switch to acoustic sound behavior. We evidence<br /> such a transition of the rotational modes by analyzing the eigen vectors of<br /> disordered frictional disks and identify upper and lower limits of the<br /> frequency-bands. We find that those are not reversed over the whole range of<br /> tangential stiffness as a remarkable difference from the rotational sound in<br /> frictional particles on a lattice. |
| DOI | 10.1103/PhysRevE.99.012906 |
| PermalinkURL | http://arxiv.org/abs/1807.08201v1 |