Wood fibres suspended in air were studied whilst flowing through a throttle. Measurements of volume fraction and velocity were compared with results from a two-fluid model simulation. Results from earlier work have shown that the lift forces acting on the individual fibres are of importance for the dispersion of volume fraction. Since the orientation of the individual fibres cannot be determined, a dispersion force was utilised to model the dispersing effect of the lift forces. The addition of a lift dispersion model significantly improved the agreement between measurement and model data. (c) 2006 Elsevier Ltd. All rights reserved.