CFD investigation of particle fluctuation characteristics of bidisperse mixture in a gas–solid fluidized bed

Particle fluctuation characteristics of a bidisperse mixture in a gas–solid fluidized bed by the multi-fluid Eulerian–Eulerian model in CFD simulation have been presented. The numerical method is verified by solid volume fraction and granular temperature experimental data from literature. The laminar and turbulent granular temperature profiles of flotsam and jetsam at different gas velocities are calculated, connecting with bubble and particle hydrodynamic behavior and flow pattern in the fluidized bed. The computed vertical turbulent energy spectra of flotsam and jetsam are compared and applied to indicate the particle motion intensity and inhomogeneity of turbulent energy dissipation. The energy spectra capture the Levy–Kolmogorov law in inertial range at high frequency. The flatness factor of wavelet decomposition coefficients of particle fluctuating velocity is shown to analyze the flow field intermittence variation with position and gas velocity. Moreover, the diffusivities for flotsam and jetsam are calculated to measure the mass transfer quality of particles.

► We simulate the dynamic behavior of a bidisperse mixture by multi-fluid CFD model.
► The laminar and turbulent granular temperature of flotsam and jetsam is calculated.
► The computed vertical turbulent energy spectra of flotsam and jetsam are analyzed.
► The intermittence variation with operation conditions is shown by flatness factor.
► The diffusivities for flotsam and jetsam are calculated to measure the mass transfer.