カオスと不可逆性の値 切断式サスペンションのカオスと不可逆性の値
D J Pine1, J P Gollub, J F Brady
1Department of Chemical Engineering and KITP, University of California, Santa Barbara, California 93106-5080, USA. pine@nyu.edu
Nature
|December 16, 2005
まとめ
研究者は,ゆっくり切断されたサスペンションで時間の逆転性がどのように失敗するかを実験的に観察しました. 濃度に依存するストレイン値により,粒子の構成は予測不可能な状態になり,アニゾトロプ的ランダムウォークに似ています.
科学分野:
- 統計物理学 統計物理学とは
- 柔らかい物質の物理学
- 非均衡のシステムとは
背景:
- タイムリバーシブルな運動方程式は,多体系において不可逆的な行動につながる可能性があります.
- この移行は根本的ですが,多くのシステムでは実験的に観察されていません.
- 低レイノルズ数流体の流れは,剪定型ニュートン流体やサスペンションのように,典型的には時間逆行性である.
研究 の 目的:
- ゆっくり切断されたサスペンションにおける時間逆転性の失敗を実験的に実証する.
- これらのシステムにおける不可逆的な行動につながる条件とメカニズムを特定する.
- 観察された不可逆性を,混沌と予測可能性の概念と結びつける.
主な方法:
- さまざまな濃度で粒子の懸浮液の切断実験.
- 粒子の移動と構成を複数のシアサイクルで測定する.
- 粒子相互作用と混沌のダイナミクスをモデル化するための数値シミュレーション.
- 混沌とした行動を定量化するためのリヤプノフ指数の計算.
主要な成果:
- 濃度に依存するストレスの値が特定され,その値を超えると時間逆行性が失敗する.
- サイクリング後の粒子の移動は,アニゾトロプ的ランダムウォーク統計に従った.
- Lyapunov指数の顕著な成長は,値ストレスの時に観察されました.
- 実験結果は数値シミュレーションと一致した.
結論:
- この研究は,切断式サスペンションにおける時間逆転性障害の最初の実験的観測を提供します.
- 値ストレンは,混沌とした粒子相互作用の発生と関連しています.
- この研究は,軟質物質系におけるカオス,可逆性,予測可能性の理解を橋渡ししている.
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