Description Many industrial and environmental flows can be categorised as particulate flows in yield-stress fluids (e.g. waste disposal, concrete, drilling muds, food processing, flows of slurries and lava). Yield-stress fluids behave like solids when the applied stress is less than the yield stress and start to flow otherwise. Examples include toothpaste, gels, concrete, waxy crude oils, etc. This exceptional behaviour helps yield-stress fluids to hold particles statically buoyant in some circumestances. In this study, we want to use computational fluid dynamics to study the complex particle sedimentation in yield-stress fluids. Key Objectives Literature survey on the topicAdapt CFD tools for numerical simulation of the problemPropose a mathematical model for drifting angle and other features of the problemCompare the computational results with the mathematical models