arXiv:2602.23188cs.LGphysics.flu-dyn2026-02

用稀疏观测数据快速调整流体模拟模型,精度接近重训练但耗时极少。

Efficient Adaptation of ROMs for Unsteady Flows Using Data Assimilation

  • 用变分自编码器与注意力机制构建可调参数的降维模型
  • 仅需少量观测数据即可实现外推区域的高精度预测
  • 适合需要快速响应的工程仿真与不确定性量化场景

我们提出一种高效的参数化降阶模型(ROM)再训练策略,在仅使用稀疏全系统观测数据的情况下,达到与完整重训练相当的精度,同时计算时间大幅降低。该架构采用编码-处理-解码结构:变分自编码器(VAE)进行降维,变压器网络演化隐状态并建模动力学。模型以雷诺数为外部控制变量,利用注意力机制捕捉时间依赖性和参数影响。概率性VAE支持轨迹集合的随机采样,通过前两阶矩提供预测均值与不确定性量化。初始训练后,仅凭少量数据即可将模型适配至样本外参数区域。其概率框架自然支持集合生成,我们将其嵌入集合卡尔曼滤波框架中,从极少量观测重建全状态轨迹。进一步发现,对样本外预测而言,主要误差来源是隐空间流形的畸变,而非隐动态变化。因此,再训练可仅限于自编码器部分,实现轻量级、计算高效的适应过程,且所需微调数据极为稀疏。

原文摘要 · Abstract (English)

We propose an efficient retraining strategy for a parameterized Reduced Order Model (ROM) that attains accuracy comparable to full retraining while requiring only a fraction of the computational time and relying solely on sparse observations of the full system. The architecture employs an encode-process-decode structure: a Variational Autoencoder (VAE) to perform dimensionality reduction, and a transformer network to evolve the latent states and model the dynamics. The ROM is parameterized by an external control variable, the Reynolds number in the Navier-Stokes setting, with the transformer exploiting attention mechanisms to capture both temporal dependencies and parameter effects. The probabilistic VAE enables stochastic sampling of trajectory ensembles, providing predictive means and uncertainty quantification through the first two moments. After initial training on a limited set of dynamical regimes, the model is adapted to out-of-sample parameter regions using only sparse data. Its probabilistic formulation naturally supports ensemble generation, which we employ within an ensemble Kalman filtering framework to assimilate data and reconstruct full-state trajectories from minimal observations. We further show that, for the dynamical system considered, the dominant source of error in out-of-sample forecasts stems from distortions of the latent manifold rather than changes in the latent dynamics. Consequently, retraining can be limited to the autoencoder, allowing for a lightweight, computationally efficient adaptation procedure with very sparse fine-tuning data.

降阶模型数据同化流体模拟不确定性量化

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