DEM-CFD Analyses of Flexible Fiber Fluidization

Gas-fluidized beds of flexible fibers are investigated using the coupled approach of Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). Gas-fiber interactions are modeled by calculating the interaction force for each constituent element in the fiber, rather than the resultant force on the whole fiber, as is typically done in DEM-CFD simulations. This treatment enables improved fluid field resolution. Pressure drop and fiber orientation results for rigid fibers with various aspect ratios are in good agreement with previous experimental and simulation results. Novel results consider the effect of fiber flexibility. Larger gas-fiber interaction forces (before the bed is fluidized) and smaller minimum fluidization velocities are observed for more flexible fiber beds, which have smaller porosities. Both the fiber aspect ratio and the fiber flexibility impact on the solids mixing rate by affecting the minimum fluidization velocity.