Origins of Stochasticity: Turbulent Fibre Suspensions

Fibres can be kept dispersed at headbox concentrations by turbulent mixing, but the forming process occurs in decaying turbulence during dewatering in a few tenths of a second.

Flocs form stochastically; network consolidation results in a stochastic porous medium.

Statistical geometry helps understand the evolution of structures involved, and their variability. The raw material, fibres, is itself inherently variable as Figure 1 shows.

  

Figure 1: Coarseness/length fractions for stone groundwood (upper sequence of larger points) and refiner groundwood (lower sequence of smaller points), each averaged over three pulps made from 30% spruce and 70% balsam fir. Composed from Marton and Robie 1969.