Eulerian-Lagrangian simulations of settling and agitated dense solid-liquid suspensions – achieving grid convergence

Eulerian-Lagrangian simulations of solid-liquid flow have been performed. The volume-averaged NavierStokesequations have been solved by a variant of the lattice-Boltzmann method; the solids dynamics byintegrating Newton’s second law for each individual particle. Solids and liquid are coupled via mappingfunctions. The application is solids suspension in a mixing tank operating in the transitional regime (theimpeller-based Reynolds number is 4,000), an overall solids volume fraction of 10% and a particle-liquidcombination with an Archimedes number of 30. In this application, the required grid resolution is dictatedby the liquid flow and we thus need freedom to choose the particle size independent of the grid spacing.Preliminary hindered settling simulations show that the proposed Eulerian-Lagrangian mapping strategyindeed offers this independence. The subsequent mixing tank simulations generate grid-independentresults.