物理方程约束的机器学习流场时程表征方法

PHYSICAL CONSTRAINED MACHINE LEARNING MODEL FOR FLOW TIME HISTORY REPRESENTATION

  • 摘要: 机器学习是流场表征的有效研究手段,基于数据驱动的神经网络模型缺乏物理机制的可解释性,且在可用训练样本较少时数据驱动的训练方法难以获得准确的模型。针对此问题,该文构建了流场测点时程的人工神经网络模型,并辅以流体的控制方程修正模型的输出,提出了考虑物理约束的流场时程机器学习表征方法。采用神经网络方法来表征不同位置处的流场时程,并用已知测点处的样本时程进行模型训练;使用模型的输出计算流动控制方程的误差,用以修正数据驱动的模型参数。以低雷诺数方柱绕流场为例,讨论了流场时程特征表征模型的可行性和物理约束方法的精度。结果表明:该文提出的方法通过引入流动控制方程的约束,使得模型可在较少已知测点数据的情况下获得更准确、更符合物理规律的流场时程表征模型。

     

    Abstract: Machine learning is an effective method for flow representation. Data-driven machine learning models lack the interpretability of physical mechanisms, and it is difficult to obtain accurate models when there are few training samples available. An artificial neural network model using flow time history data of measurement point is proposed. The output of the model is further improved using flow governing equations, resulting a machine learning model of the flow time history considering physical constraints. The neural network model is proposed to represent the flow time history data at different locations, and the model is trained with known measurement point samples; then the model output is used to calculate the loss of the Naïve-stokes equations to improve the purely data-driven model parameters. The model is verified using flow time history data around square cylinder at low Reynolds number, and it is demonstrated that the physical constraint method can improve the accuracy of the results. The method proposed in this paper is applicable to the analysis of flow data based on measurement points, and the model accuracy is improved by introducing constraints on the flow governing equations, making the model more accurate and more consistent with the physical laws for the flow time history representation with limited available measurement data.

     

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