Development of a non-intrusive and efficient flow monitoring technique: The space-time image velocimetry (STIV)

A novel image analysis technique for measuring river surface flow is proposed. When we assume that the brightness distribution of river surface image is convected with the surface velocity, a space-time image for a searching line set parallel to the main flow would indicate velocity information as its image orientation. The new technique, the space-time image velocimetry (STIV), is capable to measure the orientation angle of the pattern using the eigenvalue analysis of the local space-time image. The performance of STIV is compared with the other image analysis technique, the large-scale particle image velocimetry (LSPIV), previously proposed by the authors and it is shown that STIV is an alternative image analysis method for measuring streamwise velocity distributions efficiently.