Effect of Stokes Number on Particle Deposition in Particle-Laden Turbulent Pipe Flows

The ability to predict particle dispersion, interaction and deposition in pipes is of value in improving the transport and process efficiency of high concentration particulate flows. In this work, the settling and deposition behaviour of suspensions of dense particles in a cylindrical pipe has been studied using direct numerical simulation coupled with Lagrangian particle tracking, with the influence of Stokes number on deposition examined. Fully developed particle-laden pipe flows are first driven to a steady state with shear Reynolds number, Reₓ =720, and particle Stokes numbers, St⁺ = 5.55 and 16.78, with the constant pressure gradient forcing term subsequently decreased until the onset of particle deposition. From the analysis performed, it can be concluded that particle deposition is sensitive to Stokes number. Particle dispersion function and mean displacement values are demonstrated to decrease considerably faster with time at the higher Stokes number. Particle migration towards the lower wall regions of the pipe also shows the formation of a bed for such particles, whilst over the same time period only dune-like structures are produced at the lower Stokes number. An analysis of the particle dynamics, carried out by examining probability density functions of particle velocities and positions, confirms these findings.