Modeling of Round Buoyancy Driven Particle Clouds.

A numerical model was developed to investigate the dynamics of round buoyancy driven particle clouds in a quiescent ambient. The developed model was validated and then applied to a range of test cases including releases of positively/negatively buoyant particles. The cloud was modeled using the standard Morton et al. (1956) entrainment assumption, and the flow field induced by the cloud was approximated as a Hill's spherical vortex. The buoyancy of the cloud was calculated as the sum of the buoyancy contributed by all particles within the cloud. Individual particles were tracked using a particle tracking equation considering the forces acting on individual particles and the computed induced velocity field. Particle--particle interactions were modeled as both elastic and inelastic collisions. The turbulent dispersion of particles was also considered and estimated using a random walk model. The model was validated by comparing simulations with the experimental and numerical results of Wang et al. 2016. The limitations of the model were then discussed.