Interface-resolved simulations of dense particulate flows: Studies on sedimentation and slurry pipe flow

Dense suspension flows, both in the natural environment and industrial settings, are complex phenomena with significant implications. From rivers shaping landscapes to industrial processes involving slurry transport, these flows hold a prominent position in numerous sectors. This thesis delves into a specific facet of these intricate flows: slurry transport within horizontal pipes. Slurry, a mixture of solid particles and a viscous fluid, presents a challenging arena due to its dynamic nature, encompassing multiple flowregimes and diverse phenomena that govern its behavior. This research seeks to unravel the complexities of slurry transport, presenting a comprehensive analysis using interface-resolved Direct Numerical Simulation (DNS). In the context of slurry
transport (also referred to as sediment transport), a horizontal pipe is a conduit where particles suspended in a viscous fluid are transported. The dynamics of this transport are governed by several dimensionless numbers, each highlighting distinct aspects of
the flow. Prominently, in this work we explore the role of the Reynolds number (Re) which encapsulates the balance between inertial and viscous forces, the Galileo number (Ga) which characterizes the competition between inertial and viscous effects in particle settling under gravity, and concentration of particles which has an influence on particle-particle and particle-fluid interactions. Key flow dynamics that determine the behaviour of the flow include turbulent mixing, gravitational settling of particles, and shear-induced particle migration due to particle-stress gradients. Practical applications of slurry transport are numerous, spanning industries such as mining, agriculture, and chemical processing. Slurry transport is of particular relevance to the dredging industry in the Netherlands to maintain its inland waterways and for land reclamation projects. However, pipeline operators grapple with issues ranging from pressure drop and the prevention of bed formation to the control of excessive pipe abrasion, silting risks, and production instability. These challenges stem from the intricate interplay of particle behavior, fluid dynamics, and pipeline geometry....