a) Particle laden flow in a coaxial pipe expansion corresponding to the experimental setup of Sommerfeld et al.. Particle size distribution between 5 and 150 microns.  The main circular port contains fluid seeded with particles.  The secondary annular port contains swirling fluid.  Approximately 1.5 Million independent particle trajectories are tracked at statistically steady state conditions.  Particles are modeled as point particles (neglect volume, wakes, etc) but there is two-way coupling between solid particles and carrying flow, through momentum exchange terms in the NS equations.

Animation #9 2.01 MB:   Visualization of the flow using contours of the streamwise velocity component and of the particulate phase. Several spanwise sections of the coaxial domain are also shown.

Animation #10 9.95 MB:  Comparison of particle trajectories for different diameters allowing comparison of the particle residence times.  Heavier particles with more inertia penetrate the recirculation region at the upstream part of the expanded region easier than small particles.