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6 Applications: Two-Region Pebble Beds
Fig. 6.26 Central region boundary under different loading ratios
Fig. 6.27 Volume of the
central region
a significant effect on the size of the central region. Results show that the size of the
central area is always the smallest under the “L − H − L” condition, followed by
the mono-density case, and then it is the largest under the “H − L − H ” condition.
It is concluded that the size of the central region can be reduced by increasing the
density of middle pebbles, while it is increased when the density of side pebbles
increases.
6.3.4 Stagnant Condition
6.3.4.1 Flow Pattern
The flow trajectory of labeled pebbles under different loading modes are investigated
here to explore the effect of pebble density on flow field characteristics. Figure 6.28
shows the flow pattern of the labeled pebbles with the heights from 0.8m to 1.0m
at the initial state, which is marked in red. It can be seen that the pebbles in the
center of the packing structure flow faster than the side pebbles, especially for in the