Modeling and simulation of granular flows for industrial applications

In this work a multibody collision model, amenable to large-scale computation, is developed to simulate near-field granular flows. This model is developed by computing momentum exchange to account for different force interactions: (1) grain-grain interaction, (2) grain-surface interaction, and (3) grain-fluid interaction. The grain-grain interactions consist of collisions as well as near-field interactions. While a general computational framework is developed in this work, specific applications to material removal by particulate flows and cleaning of surfaces will be considered. For the material removal application, the goal is to planarize an initially rough surface. For the grain-surface interaction, a material removal model is developed so that when a grain strikes the surface an appropriate amount of material is removed. Employing this model, inverse problems are then constructed where combinations of the abrasive grain size, the grain size distribution, and the flow velocity are sought to maximize the efficiency of the process. For the second application a granular-jet simulation is developed. This simulation is used to predict the cleaning effect of a jet impinging on a surface as a function of the process parameters. The analysis of these flows is separated into three components: (1) volume averaged quantities, (2) average surface tractions, and (3) average outflow conditions. For the surface stress and outflow calculations, parametric studies are performed on various process parameters. Finally, an asynchronous algorithm is developed for the solutions of near-field granular flows. In the granular flow problems considered in this work there is a disparity in the time step size necessary for the convergence of the algorithm and the time step size necessary to accurately resolve collisions. The goal of the asynchronous scheme is to allow large global time steps (the time step size required for convergence) while still accurately resolving multiple collisions within the global time step.