Comparison of particle-resolved DNS (PR-DNS) and non-resolved DEM/CFD simulations of flow through homogenous ensembles of fixed spherical and non‐spherical particles

Abstract

Particle-unresolved Eulerian/Lagrangian simulations (DEM/CFD) of static homogenous particle ensembles are compared to direct numerical simulations (DNS) performed with the Lattice-Boltzmann method (LBM). Eliminating particles’ motion, the accuracy of the CFD can be examined in a targeted way. Local quantities at the particle scale such as drag, lift and Nusselt numbers are thus evaluated in detail. In particular, the influence of particles’ shape on numerical accuracy of the non-resolved DEM/CFD utilizing different correlations is studied. As particle shapes spheres, cylinders and cubes are examined applying the widely used multi-sphere method (MSM) for particle approximation. The simulations are conducted for two different exemplary voidages of epsilon = 0.6 and epsilon = 0.8 in the Reynolds number range of R_ep = 10 – 300 and the Prandtl number P_r = 1. The study reveals issues related to non-resolved DEM/CFD simulations especially in the case of non-spherical particles and provides important details for general DEM/CFD applications as well as for future closure derivations.