用图卷积与张量分解构建可外推的时间动态模型,适用于复杂几何的参数化系统。
Time Extrapolation with Graph Convolutional Autoencoder and Tensor Train Decomposition
- 通过张量分解将高保真数据拆分为参数、空间和时间核心,实现结构化降维。
- 结合算子推理学习核心变化规律,在训练外数据上仍保持高精度预测。
- 适合需要长期外推且几何复杂的物理系统建模,如热传导与涡激振动。
图自编码器在非线性降阶建模中受到关注,尤其适用于定义在非结构网格上的参数化偏微分方程。尽管其能保持复杂域的几何一致性,但在参数化动力系统中进行超出训练数据范围的时间预测(即外推)仍具挑战,因需同时满足时间因果性和参数空间泛化能力。本文探索将图卷积自编码器(GCAs)与张量列车(TT)分解及算子推理(OpInf)结合,构建时间一致的降阶模型。具体而言,高保真快照通过TT分解表示为参数、空间和时间核心的组合,而OpInf用于学习这些核心的演化。此外,基于深度算子网络(DeepONet)框架,提出多保真两阶段方法,将空间和时间核心作为主干网络,参数核心作为分支网络,提升泛化性能。数值实验涵盖热传导、对流-扩散与涡激脱落现象,结果表明该方法在复杂几何下有效学习外推动态,优于当前先进方法如MeshGraphNets。
原文摘要 · Abstract (English)
Graph autoencoders have gained attention in nonlinear reduced-order modeling of parameterized partial differential equations defined on unstructured grids. Despite they provide a geometrically consistent way of treating complex domains, applying such architectures to parameterized dynamical systems for temporal prediction beyond the training data, i.e. the extrapolation regime, is still a challenging task due to the simultaneous need of temporal causality and generalizability in the parametric space. In this work, we explore the integration of graph convolutional autoencoders (GCAs) with tensor train (TT) decomposition and Operator Inference (OpInf) to develop a time-consistent reduced-order model. In particular, high-fidelity snapshots are represented as a combination of parametric, spatial, and temporal cores via TT decomposition, while OpInf is used to learn the evolution of the latter. Moreover, we enhance the generalization performance by developing a multi-fidelity two-stages approach in the framework of Deep Operator Networks (DeepONet), treating the spatial and temporal cores as the trunk networks, and the parametric core as the branch network. Numerical results, including heat-conduction, advection-diffusion and vortex-shedding phenomena, demonstrate great performance in effectively learning the dynamic in the extrapolation regime for complex geometries, also in comparison with state-of-the-art approaches e.g. MeshGraphNets.
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