Application of the Lattice-Boltzmann-Method in Two-Phase Flow Studies: From Point-Particles to Fully Resolved Particles

Abstract

The Lattice-Boltzmann-Method (LBM) is a powerful and robust approach for calculating fluid flows in complex geometries. This method was further developed for allowing the calculation of several problems relevant to particle-laden flows. For that purpose two approaches have been developed. The first approach concerns the coupling of the LBM with a classical Lagrangian procedure where the particles are considered as point-masses and hence the particles and the flow around them are numerically not resolved. As an example of use, the flow through a single pore was considered and the deposition of nano-scale particles was simulated. The temporal evolution of the deposit structures is visualised and both the filtration efficiency and the pressure drop are simulated and compared with measurements. In the second developed LBM-approach, the particles are fully resolved by the numerical grid whereby the flow around particles is also captured and it is possibly to effectively calculate the forces on complex particles from the bounce-back boundary condition. As a case study the flow around spherical agglomerates consisting of mono-sized spherical primary particles is examined. Using local grid refinement and the curved wall boundary condition accurate simulations of the drag coefficient of such complex particles could be performed. Especially the effect of porosity on the drag was analysed. Finally, a scenario with moving particles was considered, namely, the sedimentation of a cluster of particles. In these simulations the primary particles were allowed to stick together and form agglomerates.