5% - eTheses Repository - University of Birmingham

equations. Such a discrete vortex model would also allow for
investigation of deposition trajectories and also accommodate
representation of the jetting fraction.
Notwithstanding its declared limitations, our simple model has
provided valuable insight into assessing the balance of
mechanisms responsible for entrainment, retention and deposition
in flows that are dominated by crest-shed shear layers.
5 CONCLUSIONS
Our model has shown that any particle entering a shear eddy of
growth rate G displays one of three distinct outcomes depending
on the vortex initial radius R 0 , angular speed A0 and the
particle fall speed V. For values of A0R 0 /V~1.25 and A 0R0 °- 72 ~42G+0.03 the
particle is expelled from the vortex and could subsequently be
engaged by adjoining eddies or be deposited on the bedform.
Comparisons with published data and our own measurements broadly
supports the picture developed here, certainly sufficient for us
to reasonably recommend further development. However, more
complex zones such as reattachment will probably call for a
fuller simulation, for which we recommend the adoption of a
discrete vortex model. Perhaps the major message delivered here
is that the dynamical interaction between particles and eddies
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