Clustering of flexible fibers in riser flows is investigated using a
hybrid approach of Discrete Element Method and Computational Fluid
Dynamics. Unlike spherical particles, the flexible fibers possess
elongated shape, undergo significant deformation, and dissipate kinetic
energies through rapid fiber deformation. The present studies show that
these distinct features have significant impacts on the cluster
characteristics of the fibers. An increased fiber aspect ratio leads to
an increase in number and size of agglomerates, while it causes a
reduction in heterogeneity of solids distribution due to the more dilute
clusters with reduced packing densities. As the fibers become more
flexible, the heterogeneity increases, and denser clusters are obtained.
More significant effects of the fiber flexibility on the clustering are
observed for the fibers with larger aspect ratios. The increased energy
dissipation through the rapid fiber deformation enhances the clustering
by augmenting the number and size of the agglomerates.