Coupled DEM-LBM method for the free-surface simulation of heterogeneous suspensions

The complexity of the interactions between the constituent granular and liquid phases of a suspension requires an adequate treatment of the constituents themselves. A promising way for numerical simulations of such systems is given by hybrid computational frameworks. This is naturally done, when the Lagrangian description of particle dynamics of the granular phase finds a correspondence in the fluid description. In this work we employ extensions of the Lattice-Boltzmann Method for non-Newtonian rheology, free surfaces, and moving boundaries. The models allows for a full coupling of the phases, but in a simplified way. An experimental validation is given by an example of gravity driven flow of a particle suspension

PIBM: Particulate immersed boundary method for fluid-particle interaction problems

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 particulate 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 Lattice Boltzmann Method (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 Newtonian flows were conducted based on a combined LBM–PIBM–Discrete Element Method (DEM) 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

Coupled Lattice Boltzmann – discrete element method for numerical modelling of sand production

In this study, a coupled numerical approach based on Lattice Boltzmann Method (LBM) and Discrete Element Method (DEM) is employed for 2D simulation of fluid flow in porous media comprising of movable circular particles. The developed model is used for simulation of sand production which is one of the important problems in petroleum industry. The numerical tool has proved to have the capability of investigating the mechanisms involved in sand production problem. The results show that the rate of sand production is strongly affected by flow rate and confining pressure

A meso-scale model for fluid-microstructure interactions

Particle-fluid and fluid-structure interactions are important areas in particle technology. Typical processes where such interactions are prevalent include fluidized beds, filtration and sedimentation. In addition, fluid-structure interactions are significant in applications such as nuclear waste management, for example in the cementation process used to store radioactive materials, as well as in carbon capture and storage applications where the leakage of gas injected in underground geological reservoirs must be considered in hazard and risk assessments. Given the difficulties in directly measuring the propagation of cracks in solid structures, their permeability or the internal build-up of any gases, for example, numerical techniques in conjunction with non-destructive measurements are important tools of value in assessing and predicting the behavior of fluid-structure interactions. In this work, coupling between the lattice Boltzmann method and a digital packing algorithm based on the discrete element method is used to provide a basis for predicting such coupled interactions. The development of the coupled algorithm is described, with the calculations performed on a regular lattice grid and based on the momentum exchange method to evaluate the force exerted by the fluid on a solid boundary. A number of test cases are reported to allow assessment of the coupled model’s capabilities. Overall, these test cases demonstrate reasonable quantitative agreement with available analytical and experimental results for the case of a sphere settling in a liquid, and the expected qualitative behavior for the case of different orientation cylinders settling in a fluid, and for three dynamic packing processes