A Study on Inclined Sedimentation Mechanism by Using Hybrid LBM-DEM Simulation

The separation of solid particles from a fluid by means of gravity is an important operation in various engineering fields. The inclined-plate separator is often used to enhance the phase separation of the slurry in such fields as water clarification and bitumen production from oil sands. This paper presents the simulation study of the enhanced sedimentation in inclined vessel. In this study, we use a numerical simulation method based on the micromechanical fluid-particle system that couples the lattice-Boltzmann method (LBM) and the discrete element method (DEM). LBM is known to be a suitable technique for simulating fluid flow in complex and time-varying geometries with boundaries. On the other hand, DEM has attracted much attention among many researchers as a useful simulation technique for large deformation problems. With the coupling of both methods, the complex motion of solid particles in a fluid can be simulated. To verify this, the sedimentation behavior of a single circular particle is simulated in a fluid with different Reynolds numbers, and the results are compared with the finite element modeling. To investigate the relationship between the phase separation rate and the inclination angle of the vessel or the grain size distribution of the slurry, we attempted to simulate the settling behavior of multi-particle in a fluid. As a result, the global convection was occurred with increasing the inclination angle of the vessel. This phenomenon has also observed in many experiments. It cleared numerically that this convection contributes not only to the efficient draining of the fluid from the slurry, but also to the acceleration of the settling velocity. Based on these studies, it is confirmed that the numerical method coupled LBM and DEM becomes an important simulator for the evaluation of the inclined sedimentation.