On the orientation probability distribution of flexible fibres in a contracting channel flow

The development of fibre orientation distribution in a plane contracting channel flow is investigated with combining experiments and modelling. A dilute suspension of flexible wood fibres is used in the experiments. The salient feature of the suspension is the flexibility of the fibres. To model the fibre orientation probability distribution (FOPD) a diffusion–convection equation is used. The effect of random motion, in this case turbulence, is considered with translational and rotational diffusion coefficients. In addition to providing the inlet conditions, experiments are used to determine the rotational diffusion coefficient for the model. The work addresses the problems related to the above mentioned modelling method and combines the experiments and modelling in order to understand the mechanisms affecting the development of fibre orientation.