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our data set.
Figure 12 tabulates the three runs where U/V«6. The consistency
in the percentage of particles taking each of the trajectories
Ml to M7 confirms our initial assumption that the absolute values
of U and V are unimportant and that scalings should be based on
the ratio U/V.
3.2b) Jetted load concentration distribution at U/V=6
Figure 13 shows the concentration distribution for U/V=6,
generated by marking the particle positions every 0.2s from the
time that they move over the crest to the time that they land on
the lee or stoss slope downstream. 164 particles were tracked
giving 1785 footprints on the 43 grid squares. The particles
spent an average of 2.2s in suspension before settling to the
bed.
As expected, the Ml and M2 trajectories show the highest
concentrations and only low concentrations are found above the
crest height, showing that particles are not ejected into regions
above the shear layer. The peak concentration occurs at the same
elevation as the crest and at the end of the lee slope. This
peak is convincing evidence of the capacity of the shear layer
to support dispersed particles against the buoyancy forces acting
upon them.
3-11