2. • CFD is a simulation tool, which uses a power computer
and applied mathematics to model fluid flow situations.
• In 1928, the application of CFD started in fluid flow
• Daimler Chrysler was the first company to use CFD in
Automotive sector.
• Speedo was the first swimwear company to use CFD
• The adoption of CFD technology by food engineers
began in the 1990s.
Computational fluid dynamics approach
3. It provides qualitative and sometimes quantitative prediction
of fluid flow by
• Mathematical modelling (partial differential equations),
• Numerical methods (discretization and solution techniques),
• Software tools (solvers, pre- and post-processing utilities).
Computational fluid dynamics approach
4. Fundamentals
The fundamental basis of almost all CFD problems uses the set of
Navier–Stokes equations
• Governing the equation: conservation equations (Conservation of
mass, conservation of momentum and conservation of energy)
• Numerical analysis: The most important techniques are finite
difference, finite elements and finite volumes.
• Solving the flow problems
• Interpreting the solutions
Fundamentals of CFD
5. The analyst should have a knowledge to state
the problem and to use scientific knowledge to express
it mathematically
Stages in CFD
Pre-
processing
Processing
Post-
processing
Evaluation
7. Pre-processing: meshing
Create shape of the problem
domain
CAD/CAE integration
Engineering drawings
Coordinates include Cartesian
system (x,y,z), cylindrical system
(r, θ, z), and spherical system(r, θ,
Φ)
Stages in CFD
8. Initial condition involves knowing the state of
pressure (p) and initial velocity (u) at all points
in the flow.
Boundary conditions such as walls, inlets and
outlets largely specify what the solution will be.
Geometry of problem is defined .
Volume occupied by fluid is divided into discrete
cells.
Stages in CFD
Pre-processing: Initial boundary conditions
10. • It involves computer to solve the
mathematical equations of fluid
flow
• Solves thousands of equations
• Equation discretization
Sample grid established by
Gambit of FLUENT
Processing
11. • Calculation of derived variables
• Calculation of integral parameters: forces,
moments
• Visualization (usually with commercial
software)
• Simple X-Y plots
• Simple 2D contours
• 3D contour carpet plots
• Animations (dozens of sample pictures in
a series of time were shown continuously)
Post-Processing: Evaluation of
generated data
12. • Gives much better and deeper understanding of what is happening in a
particular process or system.
• Less time and cost than would be involved in laboratory testing.
• It can answer many ‘what if’ questions in a short time.
• Reduce scale-up problems
• It is particularly useful in simulating conditions where it is not possible to
take detailed measurements such as high temperature or dangerous
environment in an oven.
• Since it is a pro-active analysis and design tool, it can highlight the root cause
not just the effect when evaluating plant problems.
Advantages of CFD
14. 14
Where is CFD used? (Aerospace)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
F18 Store Separation
Wing-Body Interaction Hypersonic Launch
Vehicle
15. 15
Where is CFD used? (Appliances)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
Surface-heat-flux plots of the No-Frost
refrigerator and freezer compartments helped
BOSCH-SIEMENS engineers to optimize the
location of air inlets.
16. 16
Where is CFD used? (Automotive)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
External Aerodynamics Undercarriage
Aerodynamics
Interior Ventilation
Engine Cooling
17. Where is CFD used? (Biomedical)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
Temperature and natural
convection currents in the eye
following laser heating.
Spinal Catheter
Medtronic Blood Pump
18. 18
Where is CFD used? (Chemical Processing)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
Polymerization reactor vessel - prediction
of flow separation and residence time
effects.
Shear rate distribution in twin-
screw extruder simulation
Twin-screw extruder
modeling
19. 19
Where is CFD used? (HVAC&R)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
Particle traces of copier VOC emissions
colored by concentration level fall
behind the copier and then circulate
through the room before exiting the
exhaust.
Mean age of air contours indicate
location of fresh supply air
Streamlines for workstation
ventilation
Flow pathlines colored by
pressure quantify head loss
in ductwork
20. 20
Where is CFD used? (Hydraulics)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
21. 21
Where is CFD used? (Marine)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
22. 22
Where is CFD used? (Oil & Gas)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
Flow vectors and pressure
distribution on an offshore oil rig
Flow of lubricating
mud over drill bit
Volume fraction of water
Volume fraction of oil
Volume fraction of gas
Analysis of multiphase
separator
23. 23
Where is CFD used? (Power Generation)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
Flow pattern through a water
turbine.
Flow in a
burner
Flow around cooling
towers
Pathlines from the inlet
colored by temperature
during standard
operating conditions
24. 24
Where is CFD used? (Sports)
• Where is CFD used?
– Aerospace
– Appliances
– Automotive
– Biomedical
– Chemical Processing
– HVAC&R
– Hydraulics
– Marine
– Oil & Gas
– Power Generation
– Sports
26. CFD to analyse the flow and performance of process equipment, such as
• Baking ovens
• Refrigerated display cabinets
• Stirred tanks
• spray dryers
• Heat exchangers
• some other equipment. In design and development,
CFD programs predict
• Fluid flow behaviour,
• Transfer of heat, mass (such as in perspiration or dissolution),
• Phase change (such as in freezing, melting or boiling),
• Chemical reaction (such as combustion or rusting),
• Mechanical movement (such as an impeller turning, pistons, fans or
rudders)
• Stress or deformation of related solid structures (such as a mast
bending in the wind).
Application of CFD in food industry
27. Application of CFD in food industry: Drying
Problem
Descriptions
Model geometry Software Findings Author
Evaluation of
droplet
drying models in
a spray dryer
fitted
with rotary
atomizer
using CFD
simulation
3D Fluent The concept of
particle rigidity
prediction in a CFD
simulation was
explored and the
effect of initial feed
moisture content on
the drying models
was also studied.
Woo et al.
(2008a)
Simulation of
industrial scale
spray
dryer attached
with
a Fluidized bed,
using Reaction
Engineering
Approach (REA).
2D Fluent Smaller spray cone
angle facilitates easy
movement of particles to
the fluidized bed. The
accuracy of REA
model in predicting
the single droplet
drying kinetics was
also explained.
Jin and Chen
(2009)
28. Application of CFD in food industry: Cold
storage.
Contours of iso-temperatures in the most sensitive plane of a refrigerated truck (a)
without air ducts (b) with air ducts
29. Application of CFD in food industry:
Pasteurization
a)
Temperature (C) profiles of pasteurisation (85C) process of milk in stationary
position of can at (a) 60 s (b) 120 s (c) 240 s and (d) 360 s.
b)
c) d)
