论文标题

在低阶湍流模型中进行时间预测的经常性神经网络和基于库普曼的框架

Recurrent neural networks and Koopman-based frameworks for temporal predictions in a low-order model of turbulence

论文作者

Eivazi, Hamidreza, Guastoni, Luca, Schlatter, Philipp, Azizpour, Hossein, Vinuesa, Ricardo

论文摘要

Moehlis等人的低阶模型的时间动力学评估了复发性神经网络和基于库普曼的框架的能力。 (New J. Phys。6,56,2004)。我们的结果表明,可以通过适当训练的长短记忆(LSTM)网络获得出色的长期统计以及混乱系统的动态行为的出色复制品,从而导致平均值的相对错误和低于$ 1 \%$的波动。此外,一个新开发的基于Koopman的框架,称为Koopman具有非线性强迫(KNF),以明显较低的计算费用导致统计数据的准确性相同。此外,在短期预测方面,KNF框架的表现优于LSTM网络。我们还观察到,仅基于混沌系统的瞬时预测损失函数可以导致长期统计学的次优复制。因此,我们提出了一个基于计算的统计数据的模型选择标准,该标准即使在小型数据集上也可以实现出色的统计重建,而瞬时预测中的准确性却最小。

The capabilities of recurrent neural networks and Koopman-based frameworks are assessed in the prediction of temporal dynamics of the low-order model of near-wall turbulence by Moehlis et al. (New J. Phys. 6, 56, 2004). Our results show that it is possible to obtain excellent reproductions of the long-term statistics and the dynamic behavior of the chaotic system with properly trained long-short-term memory (LSTM) networks, leading to relative errors in the mean and the fluctuations below $1\%$. Besides, a newly developed Koopman-based framework, called Koopman with nonlinear forcing (KNF), leads to the same level of accuracy in the statistics at a significantly lower computational expense. Furthermore, the KNF framework outperforms the LSTM network when it comes to short-term predictions. We also observe that using a loss function based only on the instantaneous predictions of the chaotic system can lead to suboptimal reproductions in terms of long-term statistics. Thus, we propose a model-selection criterion based on the computed statistics which allows to achieve excellent statistical reconstruction even on small datasets, with minimal loss of accuracy in the instantaneous predictions.

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