Two‑Pulse 3D particle tracking with Shake‑The‑Box

Abstract

This study presents an approach to two-pulse 3D particle tracking using methods developed within the Shake-The-Box (STB, Schanz et al. in Exp Fluids 57:70, 2016) Lagrangian particle tracking (LPT) framework. The original STB algorithm requires time-resolved data and reconstructs 3D trajectories using a particle position prediction–correction scheme. However, dual-frame 3D acquisition systems, consisting of a dual-cavity laser and double-frame cameras, remain commonly used for many particle-image-based investigations in a wide range of flow velocities and applications. While such systems can be used to capture short Multi-Pulse particle trajectories (Multi-Pulse STB, MP-STB—Novara et al. in Exp Fluids 57:128, 2016a; Novara et al. in Exp Fluids 60:44, 2019), the most widespread application is still a single-pulse illumination of each of the two available frames. As a consequence, 3D LPT approaches capable of dealing with two-pulse recordings are of high interest for both the scientific community and industry. Several methods based on various evaluation schemes have been developed in the past. In the present study, a Two-Pulse Shake-The-Box approach (TP-STB) is proposed, based on the advanced IPR algorithm presented by Jahn et al. (Exp Fluids 62:179, 2021), in combination with an iterative scheme of reconstruction and tracking, ideally with the help of a predictor gained by Particle Space Correlation. It basically constitutes a lean version of the MP-STB technique, with lower demands on experimental setup and processing time. The performances of TP-STB are assessed by means of comparison with the results from the time-resolved STB algorithm (TR-STB) both concerning synthetic and experimental data. The suitability of the algorithm for the analysis of dual-frame 3D particle imaging datasets is assessed based on the processing of existing images from a tomographic PIV experiment from 2012. The comparison with the results published by Henningsson et al. (J R Soc Interface 12:20150119, 2015) confirms the capability of TP-STB to accurately reconstruct individual particle tracks despite the limited time-resolution information offered by two-frame recordings.