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arXiv 0909.5399cond-mat.stat-mech
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聚集-碎裂过程与波动动力学

Aggregation-Fragmentation Processes and Wave Kinetics

C. Connaughton, P. L. Krapivsky

摘要:

各向同性的三波动力学方程和非线性碎裂-聚集过程的速率方程之间存在形式上的对应关系。我们利用这种对应关系来研究解析波频功率谱的时间演化。具体来说,我们分析了一个3波湍流,其中波相互作用内核是一个常数。我们考虑强迫湍流和衰减湍流。在强迫情况下,标度函数如Kolmogorov-Zakharov理论所预期的那样发散为$x^{-3/2}$。在衰减的情况下,标度函数表现出非平凡的,迄今意想不到的,发散与代数和对数谱指数,我们计算。这种分歧导致非平凡的衰减规律的总波作用和主波的数量。所有的理论预测与高品质的3波动力学方程的数值模拟进行了验证。

英文摘要:

There is a formal correspondence between the isotropic 3-wave kinetic equation and the rate equations for a non-linear fragmentation--aggregation process. We exploit this correspondence to study analytically the time evolution of the wave frequency power spectrum. Specifically, we analyzed a 3-wave turbulence in which the wave interaction kernel is a constant. We consider both forced and decaying turbulence. In the forced case, the scaling function diverges as $x^{-3/2}$ as expected from Kolmogorov-Zakharov theory. In the decaying case, the scaling function exhibits non-trivial, and hitherto unexpected, divergence with both algebraic and logarithmic spectral exponents which we calculate. This divergence leads to non-trivial decay laws for the total wave action and the number of primary waves. All theoretical predictions are verified with high quality numerical simulations of the 3-wave kinetic equation.

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