Fluctuation and aggregation dynamics of solid–liquid flow in deep-sea mining pipelines under lateral vibration

Research on the fluctuation characteristics and the transition mechanisms of particle group motion in vibrating deep-sea mining pipelines is insufficient currently. To clarify the mechanisms behind the effects of vibration parameters and transport concentration on local particle aggregation and velocity fluctuations, this study investigates the fluctuation and unsteady characteristics of solid–liquid two-phase transport in large-scale vertical deep-sea mining rigid pipelines under lateral vibration conditions. Using a coupled Euler–Lagrange framework for simulation, the study mainly focuses on individual variables, quantitatively assessing the impact of particle concentration, pipeline amplitude, and frequency on particle velocity and local volume concentration fluctuations, elucidating the formation and transition mechanisms of particle motion patterns under different operating conditions. The results show that low-frequency vibrations promote spiral flow along the pipeline wall, enhancing the uniformity of particle distribution. Special-frequency vibrations of 0.75 Hz exacerbate local particle aggregation, increasing the concentration fluctuation rate by an additional 5% by resonance effects. An amplitude threshold exceeding 1.5 A* nonlinearly increased the unsteady characteristics within the pipeline, resulting in a notable increase in approximately 10% in the maximum particle volume concentration fluctuation. When particle concentration exceeds 50% of the rated concentration, the axial particle velocity fluctuation rate nearly doubles. These findings suggest that controlling vibration parameters and optimizing particle concentration are key to managing fluctuation characteristics, avoiding specific pipeline frequencies and ensuring the vibration amplitude below a certain threshold can help reduce aggregation and blockage risks. This is crucial for ensuring stable and efficient particle transport during deep-sea mining operations.