Euler-Euler / RANS Modeling of Solid-liquid Flow in Stirred Tanks: a Comprehensive Model Validation

Simulations of solid-liquid flow on industrial scales are feasible within the Euler-Euler / RANS approach. The reliability of this approach depends largely on the closure models applied to describe the unresolved phenomena at the particle scale, in particular the interfacial forces. In this work, a set of closure models assembled previously for this kind of application (Shi and Rzehak 2020) is further validated by comparing the predictions to a recent experiment on stirred-tank flows (Sommer et al. 2021), which focuses on dilute suspensions. The dataset used for validation comprises 14 different experimental cases, covering a wide range of particle slip Reynolds number, impeller Reynolds number, and particle Stokes number. For each case, simulation results on the solid velocity and volume fraction as well as liquid velocity and turbulence are compared with the experimental data. It turns out that by and large the experimental data are reasonably well reproduced. However, the measurements show a small but clear effect of modulation of the liquid phase turbulence by the particles. Therefore, several particle-induced turbulence (PIT) models based on the available literature are assessed as well. Our results indicate a reduction in the predicted fluctuations by all PIT models, which improves the results in cases with turbulence suppression but deteriorates those with turbulence augmentation.