Multiple viewpoint visualization of small scale flow phenomena: application to cavitation on an ultrasonic horn tip.

Accurate three-dimensional (3D) characterization of transient multiphase structures remains a persistent challenge, particularly in cavitating flows where vapor-gas interfaces evolve rapidly and exhibit pronounced 3D effects. This work presents a multiple viewpoint imaging system that delivers full 360° coverage of small scale multiphase phenomena using 30 synchronously triggered cameras and microsecond high power illumination. Two acquisition modes are implemented: a simultaneous snapshot mode providing instantaneous circumferential imaging, and a sequential mode emulating a virtual highspeed camera circling around the object of interest at effective frame rates above 6 × 104 frames per second. Application to acoustic cavitation at a 2 mm ultrasonic horn tip reveals dominant 3D asymmetries that in many cases cannot be identified from single view measurements. The importance of multiple viewpoint approach to ultrasonically induced cavitation research is further emphasized by comparison of volumes determined from single and multiple viewpoint approaches. Preliminary reconstructions using shape from silhouette method demonstrate the suitability of the datasets for volumetric reconstruction. The system offers a robust platform for spatially resolved multi‑view visualization and provides a foundation for future quantitative 3D reconstruction and validation of cavitating flows simulations.