  It is well known that the number of particles should be scaled up to enable
industrial scale simulation. The calculations are more computationally
intensive when the motion of the surrounding fluid is considered. Besides the
advances in computer hardware and numerical algorithms, the coupling scheme
also plays an important role on the computational efficiency. In this study, a
particle immersed boundary method (PIBM) for simulating the fluid-particle
multiphase flow was presented and assessed in both two- and three-dimensional
applications. The idea behind PIBM derives from the conventional momentum
exchange-based immersed boundary method (IBM) by treating each Lagrangian point
as a solid particle. This treatment enables LBM to be coupled with fine
particles residing within a particular grid cell. Compared with the
conventional IBM, dozens of times speedup in two-dimensional simulation and
hundreds of times in three-dimensional simulation can be expected under the
same particle and mesh number. Numerical simulations of particle sedimentation
in the Newtonian flows were conducted based on a combined lattice Boltzmann
method - particle immersed boundary method - discrete element method scheme,
showing that the PIBM can capture the feature of particulate flows in fluid and
is indeed a promising scheme for the solution of the fluid-particle interaction
problems.
