(44d) Computational Study of Shear Flows of Wet, Flexible Fibers Using the Discrete Element Method

Shear flow of wet and flexible fibers is investigated numerically by means of the Discrete Element Method (DEM). The formation of agglomerates in dilute shear flows is analyzed via the size and coordination number of the agglomerates formed. A bond number (Bo) is proposed to describe the relative effect of liquid-bridge force (represented by liquid surface tension) and particle inertia (represented by particle mass and shear rate). It is found that the sizes of large agglomerates in dilute shear flow are determined by the Bond number. In addition, the effects of particle aspect ratio and fiber flexibility on the agglomerate size and coordination number are examined.  For the dense flow of wet fibers, we have done a primary study on the effect of liquid-bridge interaction on the shear stresses in a concentration-fixed flow, in which the shear cell size is fixed so that the solid concentration is also fixed. In near future, we plan to do simulation studies on the stress-controlled flows of wet fibers, in which a constant normal stress is applied to the sheared bulk materials, similar to an experimental shear tester.