Modeling the Orientation State of a Pulp Suspension in a Linear Contraction Headbox: The effect of fiber-fiber interactions

摘要

The effect of hydrodynamic fiber-fiber interactions on the orientation state of a pulp fiber suspension flowing along the central streamline of a linear contracting headbox is studied numerically. A Fokker-Plank type equation is used to estimate the evolution of fiber orientation in this device. The effect of fiber-fiber interactions is modeled through an orientation diffusion coefficient which is shown to be a function of the fiber concentration, aspect ratio, flow gradients, in addition to a having a strong dependence on the orientation state of the suspension itself. The model has no unknown parameters and allows for simultaneous computation of both the suspension orientation state and the orientation diffusion coefficient. This work is motivated by the need to develop computational methods for optimization of pulp suspensions.