A numerical study of the effect of particle properties on the radial distribution of suspensions in pipe flow

• We study particle suspension dynamics via a Lagrangian–Lagrangian approach.
• Particle concentration alters the particle radial distribution even at dilute regimes.
• Inter-particle distance affects the rate and magnitude of particles radial migration.
• Size and skewness of particles affect the radius of stable annulus almost linearly.
• We observed double stable annuli at Reynolds numbers above 772.

We employ a Lagrangian–Lagrangian (LL) numerical formalism to study two- and three-dimensional (2D, 3D) pipe flow of dilute suspensions of macroscopic neutrally buoyant rigid bodies at flow regimes with Reynolds numbers (Re) between 0.1 and 1400. A validation study of particle migration over a wide spectrum of Re and average volumetric concentrations demonstrates the good predictive attributes of the LL approach adopted herein. Using a scalable parallel implementation of the approach, 3D direct numerical simulation is used to show that (1) rigid body rotation affects the behavior of a particle laden flow; (2) an increase in neutrally buoyant particle size decreases radial migration; (3) a decrease in inter-particle distance slows down the migration and shifts the stable position further away from the channel axis; (4) rigid body shape influences the stable radial distribution of particles; (5) particle migration is influenced, both quantitatively and qualitatively, by the Reynolds number; and (6) the stable radial particle concentration distribution is affected by the initial concentration. The parallel LL simulation framework developed herein does not impose restrictions on the shape or size of the rigid bodies and was used to simulate 3D flows of dense, colloidal suspensions of up to 23,000 neutrally buoyant ellipsoids.