Large eddy simulation of segregating multiphase pipe flows using Lagrangian particle tracking and Eulerian hindered settling models

Evaluating the segregation and settling of particles undergoing hydraulic transport in pipelines is critically important to many industrial installations across sectors such as minerals processing and waste management. Computational fluid dynamics can be used both to aid in their design and identify challenges in operation. To better understand the multiphase flow physics involved in such operations, the primary goal of this research is to simulate the complex particle concentration distribution in transport pipelines using large eddy simulation. This approach is coupled to a validated Lagrangian particle tracking (LPT) method that is compared with an implicit Eulerian-Eulerian (EE) approach to predict flows with low particle volume fractions to confirm the accuracy of the latter model. The EE model is subsequently applied to intermediate and high-volume fraction flows, given the volume fraction limitations of the LPT approach, with both experimental and numerical datasets compared for validation. Finally, a comparison of particle settling predicted using the EE approach coupled to a hindered settling model is compared with predictions obtained without hindered settling. Results highlight the superiority of predictions incorporating hindering, and that for the flows considered, equilibrium profiles are formed over moderate timescales of 60–80 s. In addition, hindered settling significantly reduces particle segregation at concentrations >3 vol%. Overall, the EE hindered settling approach provides a computationally efficient, yet high resolution methodology, for simulation of particulate flows typical of many industrially relevant problems. Ongoing work is employing population balance techniques to simulate flocculation break-up in solid–liquid systems.