基于二维局部掩码自监督的三维流场全局重构

Global reconstruction of 3D flow field based on 2D local masked self-supervision

  • 摘要: 流场重构在实验流体力学的超分辨率重建与反演等工程应用中具有重要价值。现有的流场重构训练模式包括监督学习与自监督学习,然而,当已有方法应用于数据量巨大的三维流场时,其目标流场规模受限于硬件显存容量,难以对整体流场进行高效预训练。针对此瓶颈,本研究以三维圆柱绕流场重构为例,提出一种基于Transformer的二维局部掩码自监督学习方法。该方法通过对三维流场的二维切片进行掩码自监督预训练,可以使模型学习三维流场的内在物理规律与空间关联性,并具备零样本泛化能力,可直接应用于下游的三维流场全局重构任务。实验结果表明,该方法仅利用4%的局部二维切片数据进行预训练,即可实现对三维流场的全局重构,且在测试集上的平均相对误差仅为6.62%。此外,通过与监督学习及全局自监督学习的多维度对比表明,本文方法可显著降低显存消耗和训练时间,监督学习和全局自监督学习方法的平均相对误差为8.87%与8.45%,本文方法重构精度更高。本文方法为高效、低资源消耗的三维流场自动化建模提供了一种新途径。

     

    Abstract: Flow field reconstruction is of great value in engineering applications such as super-resolution reconstruction and inversion of experimental fluid mechanics. The existing training paradigms for flow field reconstruction include supervised learning and self-supervised learning. However, when applied to large-scale 3D flow fields, the target flow field size is limited by hardware memory capacity, so it is difficult to pretrain the whole flow field efficiently. To address this bottleneck, this study proposes a Transformer-based two-dimensional (2D) local masked self-supervised learning method, taking the 3D flow field around a circular cylinder as a case study. By performing masked self-supervised pre-training on 2D slices of the 3D flow field, the model learns the underlying physical laws and spatial correlations of the 3D flow field while achieving zero-shot generalization capability, enabling its direct application to downstream global 3D flow field reconstruction tasks. The results show that the proposed method achieves global reconstruction of the 3D flow field using only 4% of the local 2D slice data for pre-training, with a mean relative error of 6.62% on the test set. In addition, multi-dimensional comparisons with supervised learning and global self-supervised learning show that the proposed method significantly reduces memory consumption and training time. The mean relative errors of the supervised learning and global self-supervised learning methods are 8.87% and 8.45%, respectively, indicating higher reconstruction accuracy of the proposed method. The method in this paper provides a new way for efficient and low resource consumption 3D flow field AI modeling.

     

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