Introduction to Computational Fluid
Dynamics (CFD)
CFD for simulation of dispersion, fire and explosion in
industrial plants
Webinar February 2018
1
DNV GL © 2018
SAFER, SMARTER, GREENER
Speakers
2
Speakers
Kenny Shaba
Rune N. Kleiveland
Phast and Safeti Product Manager
with extensive experience in
Technical Safety projects
(especially QRA) for both onshore
and offshore assets
Principal Specialist, Plant CFD
Solutions, DNV GL
DNV GL © 2018
13 years’ experience with
development and use of CFD
applications for the oil and gas
sector
Notes
Notes
Any questions during the webinar?
Please use the chat window on Go to Webinar control panel
to send your questions.
The questions will be collected and handled during Q&A session
at the end.
Please accept our apologies if we do not have time to answer
all your questions. In that case we will follow up with you
after the webinar.
For further inquiry, demo, test, training or quote,
please contact us:
software@dnvgl.com
3
DNV GL © 2018
Agenda
Agenda
What is CFD?
Challenges that CFD
can help address
Introduction to KFX™
- History
- Key Capabilities
- Validation
4
DNV GL © 2018
01
03
05
02
CFD vs Other
approaches
04
CFD Fire
simulation –
Case Study
06
Conclusions and
summary
What is Computational Fluid
Dynamics (CFD)?
5
DNV GL © 2018
What is CFD?
▪ CFD – “Computational Fluid Dynamics”
▪ Use numerical methods and algorithms to solve and analyse problems that
involve fluid flows
– By the use of computers
– Used for a wide range of problems and applications
▪ Goal: Accurate representation of the actual scenario in space and time
6
DNV GL © 2018
CFD – An example
CFD
User input
Results
Smoke
Fuel type
Geometry/
congestion
Dispersion
Combustion
model
Release
conditions
Weather
and
ventilation
Levels
Heavy oil
or light gas
Rich or lean
mixture
Flow
conditions/
mixing
Fire
Shape
Location
Heat loads
7
DNV GL © 2018
CFD – Pros/Cons
Based on
«fundamental»
models
- wide range of
validity
High degree of
complexity and
difficult to use
8
DNV GL © 2018
Interaction between
release (e.g. fire) and
surroundings
- Weather conditions
- Geometry
Long simulation times
Time development
- e.g. reduction in
release flow due to
blowdown
“IT
DEPENDS”
CFD vs other approaches
9
DNV GL © 2018
CFD and other approaches
Detailed
Specific/Novel
major accident
hazards
Quantitative
All Major
Accident
Hazards
Semi-quantitative
Qualitative
• CFD
• Experimentation
• Quantified Fault & Event Trees
• Consequence Analysis
• GAMES
• FRA & QRA
Critical Site
Items
• Lookups
• FMECA
• Screening cons and risk analyses
• LOPA
Site
• Hazard Identification, risk matrix
• Bow Tie
• FMEA
• Fault and Event Trees
DNV GL © 2018
10
Challenges that CFD can help address
11
DNV GL © 2018
Understand how fires interact with their physical surroundings
12
DNV GL © 2018
Understand spatial distribution of heat loads from a fire
13
DNV GL © 2018
Understand spatial distribution of blast loads from an explosion
14
DNV GL © 2018
Understanding the impact of an accidental release of Liquefied
Natural Gas (LNG) (1)
15
DNV GL © 2018
Understanding the impact of an accidental release of Liquefied
Natural Gas (LNG) (2)
Heat flux to equipment during fire
16
DNV GL © 2018
Understand how structures react when exposed to a fire load
DNV GL © 2018
Understand the development of a dense gas release
Flammable gas cloud 1 min. after start of release
Flammable gas cloud 10 min. after start of release
DNV GL © 2018
CFD Fire Simulation Case Study using
KFX™
19
DNV GL © 2018
Introduction to Case Study
20
DNV GL © 2018
Introduction to KFX™
21
DNV GL © 2018
Introduction to KFX™
“KFX™ is a three dimensional transient CFD tool for gas dispersion, gas explosion,
fire development, fire mitigation and fire extinction”.
Further research work at NTNU resulted in
the KFX™ CFD simulator.
1970’s
1980’s/90’s
First attempts of
numerical modelling of
combustion at the
Norwegian University of
Science and Technology
(NTNU).
22
DNV GL © 2018
1999
The EXSIM CFD explosion software was
acquired by ComputIT from Shell and
integrated as a module in KFX™
2000’s
Commercialized in 1999 by the
founding of ComputIT.
CompuIT offers KFX™
commercially together with
consultancy.
2015
2017
ComputIT and KFX™
acquired by DNV GL
Further development of KFX™
supported by major oil and gas
companies.
KFX™ - Key Capabilities
Optimized for
simulating releases in
complex geometries
and for large domains
Incorporates an
efficient porosity
technique for optimal
calculations
Includes a spray
model for fire
mitigation and
extinction by water
systems and liquid
releases
Includes dedicated
explosion module
(EXSIM)
Integrated with Finite
Element Models for
structural Response
Analysis
CAD Support
(Multiple formats)
23
DNV GL © 2018
KFX™ - Validation
▪ KFX™ and its sub models are extensively validated, and the validation work is
a continuously ongoing and very important activity in the further development of
the KFX™ CFD simulation tool
– Current validation work is ongoing for LNG dispersion in the US (PHMSA)
– EXSIM explosion code with new experimental data
▪ KFX™ is validated on many different levels – against analytical solutions,
scientific experiments and realistic full-scale tests – both sub-model tests
and integrated tests – against small-scale, medium-scale and large-scale
experiments – against various test configurations (obstruction types and layouts,
venting, ignition locations, fuels and more) – blind tests and “full-information”
test
▪ Validation is documented in the KFX™ Validation handbook which is supplied
with the software
24
DNV GL © 2018
Validation Example - How well can we model an actual fire ?
DNV GL © 2018
Conclusions and Summary
26
DNV GL © 2018
Conclusions and Summary
▪ CFD has many diverse useful applications
▪ Key criticisms of time/complexity etc. need to be understood in context
– Not all CFD scenarios are time/resource intensive
▪ KFX™ is a CFD tool that can simulate a large variety of release scenarios/hazards
– Gas jet fires, liquid pool fires, liquid spray fires, two-phase fires and explosions
– Transient development
– Accurate calculation of heat loads and smoke dispersion
– Detailed representation of geometry – fire interaction
27
DNV GL © 2018
Q&A
28
DNV GL © 2018
Thank you for attending
Notes
Webinar recording, presentation slides, together with a Q&A
document will be sent to all registered delegates in ~ 2 wks
Any further questions can be sent to software@dnvgl.com
For further inquiry, demo, test, training or quote,
please contact us:
software@dnvgl.com
29
DNV GL © 2018