FPM
FLUENT-based Fine Particle Model
The Fine Particle Model (FPM) is a FLUENT-based model for Eulerian simulations of the
formation, growth, transport, and deposition of particles in systems influenced by fluid flow, heat
transfer, and chemical reactions, such as in chemical reactors of the type shown below.
Flow/heat transfer
Chemical reactions
Particle dynamics
diffusion
sedimentation
A+B
thermophoresis
Heated surface
The FPM is a set of User-Defined Functions (UDFs) that work with FLUENT6 and later. The FPM
allows simulation of the formation and growth of particles in both gases and liquids. Although the
FPM permits simulations similar to Fluent’s Discrete Phase Model (DPM), the FPM is an Eulerian
model that accounts for particle-particle interactions and simulates the spatial and temporal
evolution of the particle size distribution. Whereas the DPM is typically used to simulate the
behavior of particles larger than 1 µm in diameter, the FPM is typically used to simulate the
behavior of particles smaller than 1 µm. More information about the FPM is available online at
www.Aerosols.com and at www.particle-dynamics.de. The FPM was developed jointly by
Chimera Technologies, Inc. and particle dynamics GmbH.
FPM Features
Simulates evolution of particle
size distribution
Simulates evolution of particle
chemical composition
Scheme-based GUI interface
FPM Applications
Chemical reactors
Combustion systems
Pollutant formation/growth
Extendable through FPM UDFs
Particle transport
Validated against published
theory, experimental data, and
numerical simulations
Nanoparticle sprays
Many other applications
Particle Size Distribution
The FPM solves for the spatial and temporal evolution of the particle size distribution. Many
particle size distributions can be represented as multimodal distributions, where each mode
represents a distinct population of particles. Each population is typically created from a
distinct source. For example, Fig. 1 shows a trimodal particle size distribution measured
near a road. The smallest mode represents combustion particles emitted from vehicles, the
middle mode represents background particles blowing over the road, and the largest mode
represents dirt and tire particles entrained by vehicles.
The FPM uses multiple overlapping
lognormal size distributions to
represent
such
complex
size
distributions. The use of lognormal
distribution
functions
permits
complex size distributions to be
represented with a minimum of
additional FLUENT scalars, thus
permitting computationally efficient
simulations. The output of an FPM
simulation is the value of the size
distribution parameters (e.g., mean
size and standard deviation) at each
point of interest in the simulation domain.
Fig. 1
Particle Chemical Composition
The FPM can also be used to simulate the spatial and temporal evolution of the chemical
composition of the particles. To do this, modes can be composed of multiple, immiscible
phases, and each phase can be composed of multiple species. For each additional species,
the FPM requires the solution of an additional scalar.
Figure 2 shows a schematic of a multiphase particle that can be represented with the FPM.
One phase is used to represent the solid core, and a second phase is used to represent the
liquid mantle. Each phase can include multiple components.
Fig. 2
Core: Multicomponent solid
Mantle: Multicomponent liquid
Sample Simulation: TiO2 Particle Formation
The FPM can be used to simulate particle formation and growth in chemical reactors. One
example is the formation of TiO2 particles according to the process
TiCl4 + O2 → TiO2 (gas-phase) + 2Cl2
TiO2 (gas-phase) → TiO2 (condensed-phase)
The production of gas-phase TiO2 is simulated with FLUENT, and the production of
condensed-phase TiO2 is simulated with the FPM.
Fig. 3a
TiCl4, 100 or 300 m/s, 800 K
10 mm
Wall, 300 K
0.2 m
0.1 m
O2, 100 m/s, 2000 K
CL
1.5 m
The FPM can be used to simulate the effect of reactor geometry and operating conditions on
the formation of particles. For the reactor geometry and operating conditions shown in Fig.
3a, and for a given mass flowrate of TiCl4, the FPM can be used to simulate the effect of the
velocity of the TiCl4 inlet stream on the radial uniformity of particle size. Figure 3b shows
radial velocity contours for TiCl4 inlet velocities of 100 and 300 m/s, where blue and red
indicate the maximum and minimum radial velocities, respectively. (The black arrow indicates
the main flow direction.) Figure 3c shows contours of particle diameter, where blue and red
represent minimum and maximum particle diameters, respectively. (The black arrow indicates
the main flow direction.) Figure 3c indicates that the radial distribution of particle diameter is
more uniform for the TiCl4 inlet velocity of 300 m/s than for 100 m/s. Because uniform particle
diameter is often desired, this suggests that operating with higher TiCl4 inlet velocities yields
superior TiO2 material properties. The FPM can also be used to calculate the distribution of
particle number and mass concentrations.
Fig. 3b
100 m/s
Fig. 3c
100 m/s
300 m/s
300 m/s
FPM GUI
The FPM GUI is fully integrated with the FLUENT GUI, permitting easy and reliable setting of FLUENT
parameters through FPM GUI panels. All FPM GUI panels are available through an FPM menu item. FPM
UDFs can be used to program additional microphysical expressions, such as expressions for coagulation
and condensation rates, which are then available through the FPM GUI panels.
FPM
FLUENT-based Fine Particle Model
Demo version available
Educational discount available
More details about the FPM available online at www.Aerosols.com
Copyright 2004. All rights reserved.
Chimera Technologies, Inc.
15051 Zodiac St. NE
Forest Lake, MN , USA 55025
Tel: 1-651-464-7771
Email: [email protected]
Website: www.Aerosols.com