Analysis of Interaction Between Moving Particles and a Fluid Through a Fully Resolved Immersed Boundary Method

The presence of particles in a suspension exerts a significant influence on its rheological behavior when compared to that of the base fluid. Due to the wide range of applications that use suspensions, from ketchup in the food industry to concrete in building construction, it is crucial to have a comprehensive understanding of their rheological behavior. To this end, the present thesis aimed to develop a fully resolved computational fluid dynamics model coupled with the discrete element method (CFD-DEM) to consider the behavior of particles under shear flow. A variant of the immersed boundary method was developed as a fully resolved CFD solver. The model's validation was conducted using different test cases with a limited number of particles, ensuring the model's capacity to accurately capture both long- and short-range hydrodynamic interactions. Additionally, the model was evaluated for its capacity to simulate a falling sphere in a non-Newtonian fluid, thereby demonstrating its ability to apply different non-Newtonian viscosity models. Subsequently, the coupled code was prepared for execution in parallel, and its implementation was then applied to suspensions consisting of multiple particles. Following simulation on high performance computing (HPC) resources, model validation was further extended to suspensions by comparing relative viscosity and distribution along the simulation domain with the Krieger-Dougherty and Philips models. The model's validation was further substantiated by its successful alignment with experimental data. All of these validations confirmed the accuracy of the developed model. Finally, fully resolved field data around the particles were post-processed to achieve the primary objective of the project, which was to quantify the ratio between inter-particle shear rate and global shear rate.