Coupled lattice Boltzmann and discrete element modelling of fluid–particle interaction problems

Particle–fluid systems encountered in many scientific and engineering applications impose a significant modelling challenge. This paper outlines a new solution strategy that couples lattice Boltzmann (LB), large eddy simulation (LES), and discrete element (DE) methodologies for the simulation of particle–fluid systems at moderately high Reynolds numbers. The following main computational issues are considered: (1) the use of the standard LB formulation for the solution of fluid flows; (2) the incorporation of the one-parameter Smagorinski turbulence model in the LB equations for turbulent flows; (3) the utilisation of one immersed boundary scheme for computing hydrodynamic interaction forces between the fluid and moving particles; and (4) the use of DE methods accounting for the interaction between solid particles. The new contributions made in the current work include the application of the Smagorinski turbulence model to moving particles and the proposal of a subcycling time integration scheme for the DE modelling in order to ensure an overall stable LB–DE solution. A complex transport problem involving 70 large moving particles with moderately high Reynolds number (around 56,000) is provided to demonstrate the capability of the presented coupling strategy.