On the use of particle-wall interaction models to predict particle-laden flow in 90-deg bends

The objective of this work is to evaluate the capability of different combinations of a turbulence model and a Lagrangian particle tracking (LPT) model integrating a particle-wall interaction (PWI) model to predict particle-laden flow in 90-deg bends, as well as the impact of the PWI model on the prediction of the referred flow. The experimental data from Kliafas and Holt (1987) (LDV measurements of a turbulent air-solid two-phase flow in a 90 degrees bend.Experiments in Fluids, 5: 73-85) concerning a vertical to horizontal square-sectioned duct with a hydraulic diameter of 0.1 m that are connected by a 90-deg bend with a curvature ratio of 3.52, served as the benchmark for the aimed analysis. Air with glass spheres of 50 mu m diameter flows in the experimental duct system with a Reynolds number of 3.47x10(5). The airflow was modelled by four different turbulence models: a low Reynolds numberk-epsilon model, the SSTk-omega model, thev(2)-fmodel, and the RSM SSG model. The particle-phase was modelled by a LPT formulation, and the particle-wall interaction was calculated using four different models: Brauer, Grant & Tabakoff, Matsumoto & Saito and Brach & Dunn PWI models. The 3D simulation results of mean streamwise velocities from the sixteen RANS-LPT/PWI combinations were compared qualitatively and quantitatively to experimental and numerical data available in the literature. The four turbulence models produced errors for the gas-phase in the order of 8%. Concerning the particle-phase, the errors produced by all RANS-LPT/PWI combinations were below 4% for bend angles up to 15 degrees and up to 18% for bend angles higher than 30 degrees. The best results for the particle-phase were obtained with the SSTk-omega andv(2)-fmodel combined with the LPT/Brauer or LPT/Brach & Dunn PWI models, which produced errors inferior to 14%.