用自适应采样精准定位流体失稳边界,大幅减少模拟次数。
Adaptive Sampling for Hydrodynamic Stability
- 结合分类网络与生成模型,动态聚焦高不确定性区域采样。
- 仅需少量纳维-斯托克斯模拟,即可准确识别失稳边界。
- 适合高维流体稳定性分析,尤其适用于计算资源受限场景。
本文提出一种自适应采样方法,用于高效检测参数化流体问题中的分岔边界。相较于先前基于机器学习的分类器在预选数据上训练的方法,本方法引入基于流形的深度生成模型,实现参数空间采样的自适应优化。该策略包含两个核心组件:一个分类网络将流场参数映射为分岔概率,同时采用KRnet进行概率密度估计,以生成新样本。分类输出的预测熵作为不确定性指标,指导采样集中于高熵区域,从而将计算资源导向不断演化的分岔边界。这种分类与生成建模的闭环反馈机制,类比于偏微分方程求解中的误差指示自适应策略。从均匀参数分布出发,新方法显著减少纳维-斯托克斯模拟次数,实现高精度分岔边界识别,为高维稳定性分析提供了可扩展基础。
原文摘要 · Abstract (English)
An adaptive sampling approach for efficient detection of bifurcation boundaries in parametrized fluid flow problems is presented herein. The study extends the machine-learning approach of Silvester~(J. Comput. Phys., 553 (2026), 114743), where a classifier network was trained on preselected simulation data to identify bifurcated and nonbifurcated flow regimes. In contrast, the proposed methodology introduces adaptivity through a flow-based deep generative model that automatically refines the sampling of the parameter space. The strategy has two components: a classifier network maps the flow parameters to a bifurcation probability, and a probability density estimation technique (KRnet) for the generation of new samples at each adaptive step. The classifier output provides a probabilistic measure of flow stability, and the Shannon entropy of these predictions is employed as an uncertainty indicator. KRnet is trained to approximate a probability density function that concentrates sampling in regions of high entropy, thereby directing computational effort towards the evolving bifurcation boundary. This coupling between classification and generative modeling establishes a feedback-driven adaptive learning process analogous to error-indicator based refinement in contemporary partial differential equation solution strategies. Starting from a uniform parameter distribution, the new approach achieves accurate bifurcation boundary identification with significantly fewer Navier--Stokes simulations, providing a scalable foundation for high-dimensional stability analysis.
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