The prediction of flow and orientation behavior of short fiber reinforced melts in simple flow systems

Abstract A model for the prediction of changes in fiber orientation in simple flows of fiber suspensions is proposed. Fiber interactions are modeled as randomizing forces over the rotation of fibers in closed orbits in simple shear. The resulting Fokker‐Planck type convection‐diffusion equation in orientation space is solved using a finite difference technique. The solution technique permits the use of periodic boundary condition for the convection‐diffusion equation and different initial conditions for the orientation distribution. The model predictions for simple shear flow demonstrate the interaction between the structural changes and the bulk rheological properties. The effect of non‐Newtonian fluid properties on the orientation distribution was also incorporated at the slow flow limit. Structural changes are assumed to be irreversible. The irreversibility is incorporated through an orientation distribution dependent diffusion coefficient.