PIV accuracy and extending the field of view for validation of multi-scale CFD tools

Particle image velocimetry can provide thousands of cotemporaneous velocities across a measurement plane. Though PIV is a powerful tool, the accuracies and effective operating ranges are far less certain than those of more traditional anemometers. This is due in part to instrument complexity and the diverse conditions under which these systems are used. In this paper we examine the accuracy of a PIV system for several different fields of view. Users are often interested in maximizing the FOV to capture the largest possible extent of a flow field. While there are clear tradeoffs between spatial resolution and FOV, its effect on accuracy is problematic as it depends upon a variety of interrelated measurement parameters. For this study, a PIV system was used to map the flow field in the wake of a bluff body and data was benchmarked against a laser Doppler velocimeter. Four cases were examined ranging from a FOV of 50 × 89 mm and magnification of 0.16 to 412 × 732 mm and M=0.019. We had expected pronounced degradation in accuracy with increasing FOV, but observed instead a general congruence among data sets despite such substantial FOV variations.