Investigation on 3D rotating jet breakup: a numerical approach using a VOF-LPT coupled framework

The 3D rotating sprinkler represents a key component in modern micro-irrigation systems, and its jetting process exhibits pronounced transient behaviour and complex spatial distribution characteristics. However, experimental limitations have hindered a systematic understanding of its underlying dynamic mechanisms. To address this gap, this study develops a numerical approach using rotational region technology, successfully addressing the sprinkler's complex compound rotational motion. Polyhedral meshes combined with adaptive mesh refinement are employed to enhance computational accuracy and efficiency. Through systematic comparison of turbulence models and numerical algorithms, the SST k-ω model combined with the PISO algorithm is selected as the simulation foundation, ensuring computational stability and physical authenticity. The Stress-Blended Eddy Simulation (SBES) model is introduced to overcome the limitations of traditional single-scale models in predicting droplet velocity attenuation, enabling high-precision simulation of water jet morphology and velocity. The framework coupling the VOF and LPT methods achieves the first quantitative prediction of droplet size and velocity from jet breakup in a 3D rotating sprinkler, with results validated against experimental data, confirming the accuracy and reliability of the proposed approach. This study pioneers a numerical method for simulating jet breakup morphology in 3D rotating sprinklers, overcoming the technical challenge associated with the complex motion of splitter tray within a 3D rotating coordinate system. The full lifecycle dynamics of jet breakup in such sprinklers are quantitatively analyzed for the first time. The work provides a scientific basis for performance optimization and design of 3D rotating sprinklers, offering significant theoretical value and engineering application potential.