Modeling of fiber suspension flows

Authors: Hammarström, D., Hämäläinen, J.P., Dahlkild, A. A., Jäsberg, A.A.
Document Type: Article
Pubstate: Accepted
Journal: Computers and Fluids
Year: 2007


Mathematical modeling and numerical simulation of a pipe flow of paper pulp suspension is studied in this paper. The flow of wood fiber suspensions do not follow the pressure loss curves for neither laminar, nor fully developed turbulent flow of a Newtonian fluid like pure water, but pulp suspensions often show an "S"-shaped curve for the pressure drop plotted against the average suspension velocity. Shear thinning viscosity models have been used for slow velocities, but the model predictions fail as the velocity increases. Turbulent flow of pulp suspensions has been modeled with water, but this tends to result in incorrect results. A new method incorporating a wall slip method is capable of describing two flow regimes, that is, increasing and decreasing head losses as a function of increasing velocity, for both laminar and turbulent flow. Numerical solution of the pulp model is also compared to new experimental head loss data for pulp suspensions of 1-2% mass fraction.