Hybrid particle image velocimetry with the combination of cross-correlation and optical flow method

Abstract

Through a combination of cross-correlation and optical flow method (OFM), a novel technique can benefit from the strengths of each method while mitigating the flaws each individual method contains. The hybrid Particle Image Velocimetry (PIV) method utilizes the state-of-the-art cross-correlation method to account for the relatively large displacements of particles and refine the flow field using the high-resolution analysis of OFM. Image processing techniques such as interpolation, image shifting, and Gaussian filtering are crucial for integrating the cross-correlation technique with optical flow analysis. The accuracy of the hybrid PIV method was validated using standard simulated PIV images that encompassed various parameters encountered in PIV measurements. Each set of images was analyzed by the hybrid method and three other widely used correlation techniques to verify the accuracy. Results confirmed that the hybrid method is consistently more accurate than the other methods in generating the flow vectors, especially near the boundaries. Additionally, for cases dealing with large-sized particles or small displacements, the hybrid PIV method also attains more accurate results.