基于深度神经网络的粒子图像测速算法

Particle image velocimetry based on a deep neural network

粒子图像测速(PIV)作为一种流体力学实验技术,能够从流体图像中获取全局、定量的速度场信息。随着人工智能技术的发展,设计用于粒子图像测速的深度学习技术具有广泛的应用前景和研究价值。借鉴在计算机视觉领域用于运动估计的光流神经网络,采用人工合成的粒子图像数据集进行监督学习训练,从而获得适用于流体运动估计的深度神经网络模型,并且能够高效地提供单像素级别分辨率的速度场。文中采用人工合成的湍流流场粒子图像进行初步实验评估,并讨论PIV神经网络的隐藏层输出和内在原理,同时将训练而成的深度神经网络模型与传统的相关分析法、光流法对比;随后进行射流流场测速实验,验证深度神经网络PIV的实用性。实验结果表明,文中提出的基于深度神经网络的粒子图像测速在精度、分辨率、计算效率上具有优势。

As an experimental technique for fluid mechanics, particle image velocimetry (PIV) can extract global and quantitative velocity field from images.With the development of artificial intelligence,designing PIV method based on deep learning is quite promising and worth studying.First,the authors in this paper introduce the optical flow neural network which is proposed in the computer vision community.Second,a dataset including particle images and the ground-truth fluid motions is generated to train the parameters of the networks.This leads to a deep neural network for particle image velocimetry which can provide dense motion estimation (one vector for one pixel) efficiently.The featuring of particle image extracted by the neural network is also investigated in this paper.It is found that feature matching improves the accuracy of estimation.The proposed network model is firstly evaluated by a synthetic image sequence of turbulent flow.A jet flow experiment is also carried out in this paper to validate the practicability.The experimental results indicate that compared with the traditional cross- correlation and optical flow methods,the proposed deep neural network has advantages in accuracy,spatial resolution as well as efficiency.