Influence of grid resolution, parcel size and drag models on bubbling fluidized bed simulation

- A bubble detection algorithm was developed using connected component labeling.
- Drag models have a large influence on bubble size and voidage distributions.
- EMMS drag model can be used with coarse grid and large parcel size.
- Refining CFD grid and reducing the parcel size can improve the simulation results.

In this paper, a bubbling fluidized bed is simulated with different numerical parameters, such as grid resolution and parcel size. We examined also the effect of using two homogeneous drag correlations and a heterogeneous drag based on the energy minimization method. A fast and reliable bubble detection algorithm was developed based on the connected component labeling. The radial and axial solids volume fraction profiles are compared with experiment data and previous simulation results. These results show a significant influence of drag models on bubble size and voidage distributions and a much less dependence on numerical parameters. With a heterogeneous drag model that accounts for sub-scale structures, the void fraction in the bubbling fluidized bed can be well captured with coarse grid and large computation parcels. Refining the CFD grid and reducing the parcel size can improve the simulation results but with a large increase in computation cost.