Segregation and intermixing in polydisperse liquid-solid fluidized beds: A multifluid model validation study

Multifluid model (MFM) simulations have been carried out on liquid-solid fluidized beds (LSFB) consisting of binary and higher-order polydisperse particle mixtures. The role of particle-particle interactions was found to be as crucial as the drag force under laminar and homogenous LSFB flow regimes. The commonly used particle-particle closure models are designed for turbulent and heterogeneous gas-solid flow regimes and thus exhibit limited to no success when implemented for LSFB operating under laminar and homogenous conditions. A need is perceived to carry out direct numerical simulations of liquid-solid flows and extract data from them to develop rational closure terms to account for the physics of LSFB. Finally, a recommendation flow regime map signifying the performance of the MFM has been proposed. This map will act as a potential guideline to identify whether or not the bed expansion characteristics of a given polydisperse LSFB can be correctly simulated using MFM closures tested.

Automated summary

Multifluid model simulations are important for liquid-solid fluidized beds. Particle-particle interactions play a crucial role and closure models designed for gas-solid flow regimes are not suitable. Direct numerical simulations are needed to develop rational closure terms. A flow regime map is proposed as a guideline.