Computer aided processing of flow visualization data

A numerical technique is presented for transforming flow visualization photographic records of complex flows into outputs that are typical of mathematical models. Photographs of particle-seeded flows illumined with a stroboscopic sheet of laser light are digitized and projected onto a regular grid. Repeated exposures furnish a time history of particle paths and least squares determinations are performed to calculate the velocity components at each node of the chosen grid. Approximation techniques are defined for areas where the positions of the initial and end points of particle movements are close together, and where particle traces are particularly dense.