Assessment of behavioural modification techniques on particle-laden turbulent pipe flows

In this study, particle-laden turbulent pipe flows are predicted using direct numerical simulation of the fluid flow in combination with Lagrangian particle tracking and a deterministic energy-based particle agglomeration model, with a particular focus on predicting and elucidating the dynamics of particle–particle interactions. The models used, which were developed and validated in the present work, enhance our understanding of these flows, particularly in regards to the processes which lead to particle collision and agglomeration. The energy-based agglomeration technique is used together with four-way coupling between the particles and the fluid flow to predict particle aggregation due to collision interactions within the flow. Additionally, the impact of behavioural modification techniques, which influence particle dispersion, agglomeration and ultimately particle deposition, is investigated by varying influential parameters such as the temperature and Reynolds number of the flow, and the reduced surface potential, inverse Debye length, Hamaker constant and coefficient of restitution which govern particle–particle interactions. It is concluded that electric double layer repulsion exerts little influence on collision and agglomeration behaviour, attributable to the particle diameters examined being higher in comparison to the effective range of these forces. The study further demonstrates that the restitution coefficient has a significant influence on the behaviour of particle agglomeration, with a decrease in the coefficient resulting in increased aggregation rates. Hamaker constant and Reynolds number variations also both lead to major impacts on particle–particle interaction, with collision and agglomeration events occurring more frequently for increased Hamaker constant and Reynolds number.