Development of a novel calibration procedure for SPIV underwater measurements in towing tank: Flow-based calibration

An enhancement of Stereo PIV calibration is presented. The feature of this technique is to calibrate the Stereo system directly from a uniform flow measurement. This is achieved making a first two-dimensional calibration of the measurement plane using a standard dotted target, then getting information of perspective and laser sheet thickness from some measurements of well-known flows (uniform flow). This technique results in three-dimensional measurements of high accuracy with a simple calibration phase and reduces mechanical misalignment and dot recognition errors. A very simple application of this technique is performed in towing tanks. The technique is tested to a tip vortex couple of a submarine bridge fin.