Three-dimensional CFD-DEM simulations of vibrated fluidized beds validated by real-time MRI: implications of slice-based versus full-domain analysis

This study compares real-time magnetic resonance imaging (MRI) measurements with three-dimensional CFD-DEM simulations for fluidized beds of Geldart Group D particles under non-vibrated and vibrated conditions. Simulation data were analyzed both in a central 10 mm slice, mimicking the MRI measurement, and across the full three-dimensional domain to assess the representativeness of slice-based evaluation. Bed height, bubble diameter, bubble count, and bubble rise velocity were quantitatively compared. For non-vibrated cases, CFD-DEM agrees well with MRI across all metrics and reproduces established correlations for bubble diameter and rise velocity. For vibrated conditions at 10–30 Hz and 0.5 mm peak-to-peak amplitude (dimensionless acceleration Γ < 1) and superficial gas velocities of 2–4 Umf, no systematic changes in bed expansion or bubble-scale properties was observed. These findings indicate that, for Geldart D particles operating well above minimum fluidization, gas-driven bubbling dominates bed hydrodynamics and low-to-moderate vibration intensities do not substantially alter macroscopic behavior. Comparing slice-based and full-domain analyses revealed systematic offsets in absolute values, most notably in bed height and small-bubble statistics. Thus, central-slice measurements capture hydrodynamic trends reliably but can bias absolute quantities relative to full three-dimensional evaluation. These results define a regime of weak vibration influence for Geldart D particles and provide guidance for interpreting tomographic measurements of fluidized beds.