In the
literature, Eulerian applications are used for almost all diffusion dominated
problems, so strictly speaking they are only suitable
for gas or ultrafine particle study [16]. Due to their versatile
capabilities, approaches based on the Lagrangian method have
been applied extensively for many two-phase flow problems.
In these approaches, the fluid is treated as a continuum and
the discrete (particle) phase is treated in a natural Lagrangian
manner, which may or may not have any coupling effect with
fluid momentum. De Clercq and Vanrolleghem [16] mentioned
that the Lagrangian model should not be applied whenever the
particle volume fraction exceeds 10–12%.