Computational Wind Engineering Activities at CERN · ANSYS conference & 21. Schweizer Cadfem...
Transcript of Computational Wind Engineering Activities at CERN · ANSYS conference & 21. Schweizer Cadfem...
Computational Wind Engineering
Activities at CERN
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ANSYS conference & 21. Schweizer Cadfem Users’ Meeting, 16th June 2016 Winterthur
Aniko Rakai – CERN EN-CV, CFD team
Overview
• CERN and its CFD team
• Computational wind engineering
• Demonstration on CERN Meyrin site
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Overview
• CERN and its CFD team
• Computational wind engineering
• Demonstration on CERN Meyrin site
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CERN:
Organisation européenne pour la recherche nucléaire
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Organisation européenne pour la recherche
nucléaire
Safety first!
“I believe CERN should become a role model
for an environmentally-aware scientific
research laboratory. Risk assessment and
prevention and emergency preparedness
are also key targets.”
Fabiola Gianotti – CERN Director-General
https://cds.cern.ch/journal/CERNBulletin/2016/09/News Articles/2133794
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CFD team at CERN
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• CFD studies have been carried out at CERN
since 1992, the CFD team was created in
2004 in the Cooling and Ventilation group of
the Engineering Department;
• 2-3 persons, fellows or technical students;
• 4-6 projects per year;
• www.cern.ch/cfd.
Overview
• CERN and its CFD team
• Computational Wind Engineering
• Demonstration on CERN Meyrin site
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Computational wind engineering
Use of computational fluid dynamics in wind
engineering
Wind engineering: the rational treatment of
interactions between wind in the
atmospheric boundary layer and man and
his works on the surface of Earth.
(Cermak, J.E. 1975. Applications of fluid mechanics to wind engineering – A Freeman Scholar
Lecture. J. Fluids Engng., ASME, March, 9-38.)
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Potential usage 1
Wind load definition on structures
CFD Challenge: Most important is peak
pressure, not available with RANS.
Safety benefit: Reduce risk
of breaking structures.
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http://www.roofservices.com/Home/RoofingBlog/tabid/100/
entryid/92/Prepare-the-Roof-for-Hurricane-Winds.aspx
Potential usage 2
Wind comfort study
CFD Challenge: Simulation of the extremities,
RANS is questionable.
Safety benefit:
Potentially dangerous
zones located.
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Potential usage 3
Detailed environmental emission model
CFD Challenge: Covering the wind statistics
with sufficient simulations.
Safety benefit: Awareness
of immission close to sources.
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Potential usage 4
Emergency preparedness
CFD Challenge: Identification of probable
scenarios, keeping pre-run data.
Safety benefit: Fast reaction
in case of accident,
risk assessment.
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Overview
• CERN and its CFD team at CERN
• Computational Wind Engineering
• Demonstration on CERN Meyrin site
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Goal of the preparatory project
• Build up a strategy for the calculations;
• Automatize what is possible;
• Identify stakeholders;
• Identify safety benefit for CERN and related
scenarios;
• Raise awareness of the availability of this
method.
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What is around the Meyrin site?
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0.00
0.01
0.02
0.03
0.04
N
NNE
NE
ENE
E
ESE
SE
SSE
S
SSW
SW
WSW
W
WNW
NW
NNW
0.00
0.01
0.02
0.03
0.04
All classes
MSPA41 in 2011,12,14
From CERN’s Wind Atlas
(Pavol Vojtyla)
Geometry input data• Data openly available
from Geneva canton GIS
database (Système d’information
du territoire à Genève – ge.ch/sitg)
• MN95 coordinate system
• ESRI grid raster format
for topography
• GIS shape, 3DS or DXF
format for buildings
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CERN Meyrin site
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Not a typical urban
geometry, but similar, with
important elevation change
Challenges
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• Around 200 buildings for the Meyrin site
(there are other smaller sites as well);
• 1.5km x 2km domain;
• Complex topography.
Building clean-up: Icem
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Building clean-up: SCDM
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Building clean-up: SCDM
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Building clean-up: SCDM
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Building clean-up: SCDM
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Topography clean-up: original stl
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Number of faces:
~ 24 million
Faces over 0.7 quality:
~ 8000
Quality histogram with
skewness, smaller is better
0 10.3
Face
number
count
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Topography clean-up: 1m
resolution shrink wrap
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Number of faces:
~ 7 million
Faces over 0.7 quality:
0
Quality histogram with
skewness, smaller is better
0 10.3
Face
number
count
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Topography clean-up: 3m
resolution shrink wrap
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Number of faces:
~ 0.7 million
Faces over 0.7 quality:
0
Quality histogram with
skewness, smaller is better
0 10.3
Face
number
count
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Combination of topology and
buildings: original
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Combination of topology and
buildings: after shrink wrap
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Number of faces:
~ 12.5 million
Faces over 0.7 quality:
5
Quality histogram with
skewness, smaller is better
0 10.3
Face
number
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Demonstrative calculations on a
smaller domain:Only 17 buildings in the centre:
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Pollutant source next to a building
Far field wind direction
• rke turbulence model
• SIMPLE p-v coupling
• ABL inlet
• UDS passive scalar
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Volume mesh Cell
number
Cell
number
Quality histogram with
skewness
Quality histogram with
skewness
Hexcore: 2.9 million cells in total
Cutcell: 0.9 million cells in total
Pressure load on a structure
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Suction: Potential problem
for equipment on the top
of the building
Far
field
win
d d
irection
Note: this usage is not scope of the project but
data is available after the final computations
Flow field between buildings for
wind comfort assessment
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High wind velocity in
passages
Far field wind direction
Note: this usage is not scope of the project but
data is available after the final computations
Streamlines from hypothetical
sources: local differences
Before building After building
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Local effects
Overview
• CERN and its CFD team
• Computational wind engineering
• Demonstration on CERN Meyrin site
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Conclusions and outlook
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CERN commitment for environment and
safety
Strategy built up
First demonstrative simulations
• Scenario identification
• Calculation campaign
• Validation
• Uncertainty quantification
Thank you for your attention!
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Aniko Rakai, CFD Team, CERN, www.cern.ch/cfd