Simulation of flexible fibre motion through screen apertures

Since flexible pulp fibres produce paper of higher quality than their stiff counterparts, the pulp and paper industry has a keen interest in developin g a method of fractionating fibres based on flexibility. Utilizing the nonl inear equations which represent the motion of a flexible fibre, together wi th a computational fluid dynamics analysis, the motion of flexible fibres i n a channel flow with a slot are simulated and the effect of fibre flexibil ity on the tendency for the fibres to pass through the slot is examined. Fo r the first time, a theoretical model has been used to predict that screeni ng based on fibre flexibility does occur. The results of the numerical simu lations are compared to observed experimental results. It is shown that fib re length is the primary characteristic which determines a fibre's tendency to pass through a slot and that fibre flexibility plays a secondary role.