A Novel Approach for Stereo PIV Calibration in Towing Tank

An improvement of the process of stereo-PIV calibration is presented. The central feature of the proposed technique is that the calibration of the stereoscopic system is based upon the measurement of a calibrated flow. This is achieved through an initial two-dimensional calibration of the measurement plane using a single target point, followed by a perspective and laser sheet thickness optimization that makes use of the measurement of a known reference flow, e.g. a uniform flow. This technique results in planar domain, three-component (2D-3C) measurements of enhanced accuracy with a simpler calibration phase, which compensates for the mechanical misalignment and eliminates the errors deriving from the classical target plate dot identification. The technique is particularly well suited for towing tanks and other large facilities, and is applied to the vortex system shed from an underwater bridge sail.