Study of Single Pixel Evaluation for Experimental Measurements in a Microchannel

Abstract

A newly proposed algorithm named single pixel evaluation (SPE) has been developed to increase the resolution of micro-PIV to its physical limit of one pixel. Despite the SPE is able to improve the resolution significantly in comparison with conventional cross-correlation, some phenomenon are still unknown due to its infancy, resulting in discrepancies between the analytic predictions and the experimental measurements. To provide reliable rules as applying the SPE, an overall inspection of the algorithm's behaviors is essential. This paper investigated five general factors, determining their performances via synthetic particle images subjected to a parabolic flow profile. The factors include particle image quality, particle image density, search radius (SR), particle image displacement, and particle image diameter. The results indicate that the particle image quality behaves the most significantly among the factors. Moreover, the SPE was also compared with the fast Fourier transform based cross-correlation (FFT-CC) under the equivalent signal-to-noise ratio (SNR). The tendencies of optimal values with respect to different factors are revealed in the following text. To complete the study, experiments on a straight microchannel were implemented to verify the observations from the simulations. The measured images which followed the suggested rules show better results than the other ones.