Simulations of particle dynamics in a confined shear flow

The dynamic behavior of particles injected into the high-speed shear how in the confined geometry of an axisymmetric dump combustor is studied computationally using the flux-corrected transport algorithm and a Lagrangian approach to track particles in the how. Small particles are seen to travel with the large vortical structures, while intermediate sized particles are seen to form sheets as they are ejected from these structures. Dispersion of the particles is found to be optimal at Stokes numbers on the order of unity when particles that have been deposited on the combustor walls are neglected. Further analysis shows that it is the shedding frequency that governs the dispersion, even at downstream locations where the first merging frequency governs the fluid how, This property is observed for all particle sizes studied except for cases at very low Stokes numbers, where the merging frequency, as well as the frequency obtained by combining the merging and shedding frequencies, is observed. A correlation between particle size and flow vorticity is also obtained and shows that high concentrations of particles can he associated with high vorticity for small particles, whereas the opposite is true for intermediate to large sized particles.