Suspension of Rigid Particles Settling in Density Stratified Fluids

Particulate flows comprise important environmental processes in atmosphere and ocean where the physics of the fluid is markedly affected by variation of the fluid density through temperature and/or salinity variation. Our recent study shows that the settling dynamics of a particle in a linearly stratified fluid can be significantly influenced by the presence of density gradients. Moreover, we show that the interaction between a pair of particles in a stratified fluid can substantially differ from a homogeneous fluid and stratification leads to attraction between the particles. The results suggest that the presence of background density gradient can have a direct consequence on the microstructure of particulate flows of stratified fluids.  The suspension of spherical particles is investigated in periodic cells and three-dimensional full non-linear solutions are provided to establish the fundamental effects of stratification on many-particle systems, a challenge that has to date gone unmatched. Direct comparison between the microstructure and pseudo turbulent properties of homogeneous and stratified fluids is provided.