Paper Pulp Mixing
The Colorful Fluid Mixing Gallery
Shown here is a paper pulp drop tank. Paper stock is added on the top of the vessel. Near the
bottom there is a side entering impeller, an inlet and an outlet. Water is injected at the inlet just
above the impeller. The impeller mixes the water with the paper stock, diluting the stock and
breaking down the fibers. The diluted pulp leaves the vessel through the outlet all the way at the
bottom. The bottom of the vessel has a horseshoe shape, to minimize dead zones where pulp
might build up. Paper pulp has a complex rheology and has a yield stress. A special model was
used to allow for stagnant regions, laminar regions and turbulent regions. The image shows the
velocity magnitude at the vessel wall.
Shown here is the flow pattern in a stock chest for mixing and storage of paper pulp. The image
on the top shows the flow pattern with a solution of 1% pulp. The image on the bottom shows
how the flow pattern changes when the concentration is increased to 5%. The impeller was
modeled as a simple straight jet with no swirl. These images were created in cooperation with Dr.
Richard D. LaRoche at SGI/Cray.
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Last Updated April 10, 1998 by André Bakker
© André Bakker 1998