Large Eddy Simulation of Particle-Particle Interactions in Turbulent Flow: Collision, Agglomeration and Break-Up Events

A numerical study of particle-particle interactions in a turbulent flow is performed using an Eulerian-Lagrangian particle tracking code with a

hard-sphere collision model extended to take into account coalescence between the colliding particles and break-up of agglomerates. The effect of the agglomerate fractal dimension on the break-up events, and eventually on collision and agglomeration, is presented. The computational domain was seeded with primary particles (calcite, a nuclear waste simulant) of size 60 micron and allowed to run until steady state before the particle-particle interactions were activated. Break-up events reduce as the agglomerate fractal dimension (df = 2.0, 2.5, 2.8 and 3.0) increases, and with no break-up event as the control, the effect of break-up on particle-particle interactions is presented. The results show an increase in the number of collisions, and the number of collisions leading to agglomeration, with a decrease in the agglomeration rate and agglomerate size with increasing hydrodynamic stress, as a consequence of break-up.