Modeling Just-suspended Speed
Solids suspension in mixing tanks is of interest in applications
where a reaction needs to take place between the solids and the
liquid. Much work has been done over the years to compute the "just-suspended
speed" of a mixing tank, or NJS.
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The vector plot illustrates the 2D axisymmetric
flow field in the stirred tank.
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Modeling solids distribution
The partial suspension of solid glass beads is
shown in the contour plot. Full suspension can also be predicted.
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Modeling Volume Fraction Profiles
The plot shows the volume fraction profiles of glass beads along
the outer wall for three rpm’s. The top of the vessel is at x=0
and the bottom of the vessel at the maximum x value.
At the lowest speed (black), the volume fraction
increases near the bottom of the tank. This tendency is less so
at 240 rpm (red), and even less pronounced at the highest speed
(green), where the distribution of glass is fairly uniform along
the most of the length of the wall.
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Click on image to view animation
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