Fundamentals of Particle Dynamics - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 143

Table 6.1 Advantages and disadvantages of the Lagrangian and Eulerian particle representation
Advantages Disadvantages

Lagrangian Considers microscopic transport

processes. Detailed information such
as individual particle location,
residence time, deposition sites are
available
Can handle different particle sizes and
characteristics such as mass and
heat transfer more effectively

Turbulence dispersion is idealised and its
coupling with the fluid flow is
restrictive. Full turbulence coupling is
difficult and computationally
expensive
Is not practical for large discrete phase
volume fractions. The occupied space
is not typically accounted for in the
fluid flow equations

Eulerian Computationally more economical and

can handle industrial multiphase
flow applications
Can handle both dilute and dense flows

Different size particles are treated as
different phases
Requires constitutive modelling of the
interaction forces, which are difficult
to prescribe, and may have to be
adjusted for different flow regimes

6.2.3 Linking the Fluid and Particle Equations

In Chap. 5 we derived the governing equations for fluid flow, and in this section
we have presented the equations that describe particle motion. Before moving on,
it is desirable to summarise these equations of motion and how they are linked to
each other computationally in order to give the reader a visual framework to better
understand CFPD modelling. Figure 6.4 illustrates the link between the fluid and
particle phase equations. The Eulerian-Eulerian method provides full coupling where
the phases are intermingling and interacting with each other. In each computational
cell, the volume fraction α N defines the amount of occupied space by each phase
that is present.