The theoretical and experimental work summarized in this thesis examine the flow of a vertical jet issuing into a suspension of particles. For small particle Reynolds numbers, a relative velocity (between the particle and the bulk suspension) that is a function of concentration only, and an initially homogeneous suspension, the flow field divides into regions of pure fluid and suspension, and hence, a buoyancy force is exerted on the lighter pure fluid jet. The governing two-phase flow equations are solved in different asymptotic limits to show that the jet acquires increasing plume-like characteristics as it flows downstream. A linear stability analysis on the plume-like flow solution showed that there is no critical flow parameter below which this flow is stable. The experimental work was conducted so that comparisons could be made with the theoretical predictions. The experimentally measured spreading rates of the pure fluid region agree quite well with those predicted by the theory, and verify the effect of the buoyancy force on the jet. As predicted by the stability analysis, all of the plume-like flows were unstable. Quantitative comparisons of the experimentally measured amplification rates with those predicted by the theory were inconclusive. However, the qualitative effects of buoyancy, initial jet momentum, and particle concentration in the suspension were observed to be destabilizing, as predicted by the theory.
