The two-dimensional multi-continuum approach of
Pericleous and Rhodes (1986, 1987) was well advanced
for its time and represents to some degree the direction
that modern day multiphase hydrocyclone modelling
could take. Computational resources limited the scope
of their modelling. Other authors have considered
Lagrangian particle tracking superimposed upon Eulerian
simulation, which has validity for very dilute flows
(maximum solids volume fraction 5%). Improvement
of this approach was made by Hsieh and Rajamani
(1991) adopting a coupled iterative approach, whereby
the continuous viscosity was updated and the continuous
prediction recalculated. This approach was developed
further by Devulapalli and Rajamani (1996) who
treated the Lagrangian particle tracks as representing
spreading Gaussian clouds.