Application Of Lattice Boltzmann And Immersed Boundary Methods For Particle Sedimentation In A Container With Moving Boundaries

Computational fluid dynamics(CFD)simulation of particle sedimentation plays a crucial role in predicting the performance of engineering processes for cost-effectiveness and in forecasting natural phenomena to minimize the risk of potential damage.Most CFD studies do not consider the boundary movement due to either modeling difficulty or insignificance.The Lattice Boltzmann Method(LBM)is known for its computational efficiency in modeling complex geometries.Its application to moving boundary problems requires a merger with an apt method for increased performance and accuracy.Hence,a hybrid scheme is developed that decouples the flow solution from the structure solver so that the algorithm fits parallel computation on multicore processors.The proposed method combines the LBM,an immersed boundary method(IBM),and a Hard Sphere Molecular Dynamics(HSMD)model.A Stoke's drag correlation im-plements the hydrodynamic interaction using a momentum exchange based IBM,avoiding an iterative solution.The HSMD evaluates the discrete particles' kinematics and trajecto-ry.A three-dimensional(3D)simulation of a single particle settling case is considered as a benchmark,and the simulation result exhibits a close match with the analytical solution and previous experimental results of the terminal particle velocity.The newly proposed scheme is applied to an enclosed flow induced by an elastic rect-angular container undergoing harmonic oscillations.An analytical deformation equation is used based on a thin plate linear elastic deformation theory to calculate the displacement experienced by the boundary.The hybrid LB-IBM captures the coupling between a rigid bounding surface and the hydrodynamic response of an enclosed particle-laden fluid.The results reveal that the sedimentation and particle locations are sensitive to the boundary oscillation amplitude and the subsequent changes in the flow field.Particle distribution analyses demonstrate the presence of particle structure.Despite the wall motion and the resulting intense particle collision,the turbulence level within the flow field is found to be less in quantity compared to the flow field within the stationary wall.