A coupled LES-LBM-IMB-DEM modeling for evaluating pressure drop of a heterogeneous alternating-layer packed bed

Abstract

• A LES-LBM-IMB-DEM (LLID) model was established. • The LLID model was carefully calibrated and validated. • Interface characteristics and resistance loss mechanisms of HAL beds were revealed. • A new correlation was proposed for evaluating the pressure drop of HAL beds. Packed beds composed of a heterogeneous alternating-layer (HAL) granular exist in many practical applications, such as blast furnaces of the ironmaking industry. Insights into HAL beds are significant to process performance but are still challenging and not fully understood. A coupled LES-LBM-IMB-DEM (LLID) model is established to directly obtain the interphase closure of fluid–solid systems and evaluate the pressure drop of HAL beds. The LLID model particularly involves pores turbulent flow of particle-resolved scale using the multiple-relaxation-time lattice Boltzmann model (MRT-LBM) with large eddy simulation (LES), tracking the interaction of particle–particle/walls using discrete element method (DEM), and coupling fluid-granular system using immersed moving boundary (IMB). The model was carefully calibrated concerning lattice resolution, sub-grid numbers, collocations of collision term and weight function, relaxation time, Smagorinsky constant. Also, it was verified via flowing past a particle, regular packed bed, and HAL bed, and found reasonable agreements achieved. Furthermore, the model was applied to investigate HAL beds, especially the interface characteristics, velocity and pores distribution, mechanism of interface resistance loss, and revealed the relationship of specific pressure drop between the interface region and bulk layer section. Finally, a new correlation of pressure drops for HAL beds was proposed via linking the interface pressure drop to the bulk layer.