arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0907.3910cond-mat.stat-mech
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耦合驱动扩散模型的标度性和普适性

Scaling and universality in coupled driven diffusive models

Abhik Basu, Erwin Frey

摘要:

受磁流体力学(MHD)物理学的启发,提出了一种简化的一维耦合Burgers类模型来描述一维MHD,该模型是Burgers模型在耦合自由度上的推广。除了MHD,该模型作为一个一维简化模型驱动的二元流体混合物。在这里,我们已经进行了一个全面的研究的普遍性质的广义d维版本的简化模型。我们采用分析和数值方法。特别地,我们确定了模型中相关的两点时间相关关联函数的标度指数和幅值比。我们证明,这些数量不断变化的噪声互相关的幅度。此外,我们的数值研究证实了连续依赖的长波长和长时间尺度的物理模型上的噪声互相关的幅度,在我们的分析研究中发现。我们构造并模拟了一维耦合自由度的格子气模型,属于我们的耦合Burgers类模型的普适类,表现出类似的行为。我们使用了各种数值(蒙特卡罗和伪谱方法)和分析(动态重整化群,自洽模式耦合理论和功能重整化群)的方法为我们的工作。我们不同方法的结果是相辅相成的。我们的结果在各种非平衡模型的可能实现进行了讨论。

英文摘要:

Inspired by the physics of magnetohydrodynamics (MHD) a simplified coupled Burgers-like model in one dimension (1d), a generalization of the Burgers model to coupled degrees of freedom, is proposed to describe 1dMHD. In addition to MHD, this model serves as a 1d reduced model for driven binary fluid mixtures. Here we have performed a comprehensive study of the universal properties of the generalized d-dimensional version of the reduced model. We employ both analytical and numerical approaches. In particular, we determine the scaling exponents and the amplitude-ratios of the relevant two-point time-dependent correlation functions in the model. We demonstrate that these quantities vary continuously with the amplitude of the noise cross-correlation. Further our numerical studies corroborate the continuous dependence of long wavelength and long time-scale physics of the model on the amplitude of the noise cross-correlations, as found in our analytical studies. We construct and simulate lattice-gas models of coupled degrees of freedom in 1d, belonging to the universality class of our coupled Burgers-like model, which display similar behavior. We use a variety of numerical (Monte-Carlo and Pseudospectral methods) and analytical (Dynamic Renormalization Group, Self-Consistent Mode-Coupling Theory and Functional Renormalization Group) approaches for our work. The results from our different approaches complement one another. Possible realizations of our results in various nonequilibrium models are discussed.

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