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

Abstract 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.