Evaluation of the prediction capability of mesoscale CFD models on velocity fluctuations in liquid-solid flows

Mesoscale CFD models are of great importance in multiphase flow studies due to their acceptable computational cost and great numerical fidelity. However, the evaluations of mesoscale models on velocity fluctuation predictions are still limited. An evaluation of the predictive capability of current CFD models on velocity fluctuations in liquid-solid flows is presented. Numerical simulations are carried out with both the Eulerian-Eulerian Two-Fluid Model (TFM) and the Eulerian-Lagrangian Discrete Phase Model (DPM), and compared with the available experimental data. Together with the proper models in both phases, the TFM satisfactorily predicts two-phase velocity fluctuations. A diffusion-based coupling method is implemented to mitigate the grid dependency problem in the DPM. The diffusion-based coupling method greatly improves the predictive fidelity of the particle volume fraction for DPM. However, it overpredicts velocity fluctuations for both phases. Further research is required to enhance the fidelity of velocity fluctuation prediction in fluid-particle flow simulation models. •The TFM and DPM with mesoscale models are evaluated on their prediction fidelity of two-phase velocity fluctuation.•With the appropriate models, the TFM could predict velocity fluctuations in both phases satisfyingly.•A diffusion-based method is incorporated into DPM to mitigate the grid-dependent problem.•The diffusion-based DPM could not generate accurate predictions of velocity fluctuations in both phases.•Further study is required for the failed velocity fluctuations prediction in DPM.