RapidPIV: Full Flow-Field kHz PIV for Real-Time Display and Control

Abstract

We present a novel architecture for accelerating PIV calculations. An optical flow hardware accelerator does the brunt of the work, with cross-correlation only providing quick corrections. The result is RapidPIV: a free-to-download software program for real-time particle image velocimetry (PIV) for Linux and Windows computers with an Nvidia Turing-gen (or newer) GPU (RapidPIV download at https://rapidpiv.caltech.edu). Dense vector fields and vorticity can be displayed in real time when connected to compatible camera. Processing pre-existing PIV image files is also supported. We achieve 1,150 frames-per-second on 1 megapixel images. Accuracy, repeatability, and robustness are tested with physical experiments involving an accelerated flat plate and a cylinder wake. RapidPIV's accuracy, precision and ability to handle high displacement, velocity gradients, out-of-plane motion, and low seeding density compare favorably with the trusted multi-grid correlation software. However, RapidPIV is a thousand times faster.