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KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
CFD AND VIRTUAL REALITY FOR AIRFLOW VISUALISATION
Kjeld SvidtDept of Building Technology and Structural Engineering
Aalborg University
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Contents
BackgroundMethodsFacilitiesCasesResults and conclusions
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
The IT in Civil Engineering groupat dept of Building Technology
• Professor Per Christiansson (1998) (former KBS-Media Lab, Lund University and the IT Bygg program in Sweden)
• Assistant Prof. Kjeld Svidt• PhD student Yoke-Chin Lai
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
The IT in Civil Engineering group.Research areas and projects
• Virtual Buildings and Collaboration– ’Distributed Virtual Workspace for enhancing
Communication within the Construction Industry - DIVERCITY’ (EU IST)
– ’It in Collaborative Design’ (Danish Centre for Integrated Design, CID)
• Knowledge Nodes for Knowledge Transfer– (SERFIN, Merkurius, e-learning)
• Digital Cities and Intelligent Buildings
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
CFD at dept of Building Technology- indoor environmental engineering group
Airflow in and around buildings Office buildings Industrial and livestock buildings Mechanical, natural and hybrid ventilation Thermal comfort Air quality Energy efficiency
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
CFD Model of Incineration Hall, Amagerforbrænding
67 m
50 m
21 m
Displacement Ventilation SupplyCase C-D
Outdoor Air SupplyCase E-H
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Comparison between Calculated and Measured Results
- Amagerforbrænding
Vertical Plane at Incineration LineFillTemperature
52 oC46 oC40 oC34 oC28 oC22 oC16 oC10 oC
35o43o
34o
12-18o30-35o
53o
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Airborne transmission of respiratory disease between pig units located at close range (CEPROS) 1%
Ref: Bjarne Bjerg, KVL
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Airborne transmission of respiratory disease between pig units located at close range (CEPROS) 0.2%
Ref: Bjarne Bjerg, KVL
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Airborne transmission of respiratory disease between pig units located at close range (CEPROS) 0.1%
Ref: Bjarne Bjerg, KVL
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Test of VR in a specific project
Research project: “Control of Air Movement in Livestock Buildings”
... a joint research project between three Danish research groups:
The Royal Veterinary and Agricultural University, Department of Animal Science & Animal Health, Copenhagen, Denmark
Danish Institute of Agricultural Sciences, Department of Agricultural Engineering, Research Centre Bygholm, Horsens, Denmark
Aalborg University, Department of Building Technology and Structural Engineering, Aalborg, Denmark
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Why livestock buildings
Livestock production an important export industry in Denmark
Increased focus on working environment, indoor air quality, animal welfare
New housing types and production systems
New design tools such as Computational Fluid Dynamics
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
The VR part of the project
One-day information seminar for professionals in the ventilation industry and consultants from the agricultural extension service.
For this seminar, a few cases reflecting research results as well as problem-cases from the industry were selected to be presented in the Virtual Reality facilities at Aalborg University.
Airflow was calculated with the commercial CFD-code Fluent version 5.5. Results were displayed with VU visualisation software (www.cerca.umontreal.ca/vu).
The results were displayed with active stereo in the panorama as well as the six-sided CAVE.
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
What is Virtual Reality ?
Presentations that take place at the VR-Centre ?
Convincing your senses that something virtual is real
Realistic visualisation of phenomena which are difficult to see in reality (e.g. airflow)
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Virtual Reality may include the following elements:
Stereo viewing (different pictures for right and left eye)• Passive (polarized or colour filter)• Active (shutter glasses)
A certain degree of immersion• Wide screens, power walls• Large curved screens • CAVE• Head mounted displays
Realtime interaction with the model/database• Mouse or keyboard• Tracking of persons or interaction devices• Haptic devices
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
VR facilities at Aalborg University (1)
Onyx2 IR2(will be replaced by PC cluster 2003)
LightwaveMatrix-Hub
Cave
Panorama
3D Auditorium
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
VR facilities at Aalborg University (2)
• Panorama– Ø 7.1m, 160°, H 3.5m– Mono & aktive stereo– 28 persons– Tracking
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
VR facilities at Aalborg University (3)
• 6-sided CAVE– 2.5m x 2.5m x 2.5m– Back projektion– Aktive stereo– 1 person with tracking,
+ a few observers without tracking
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
VR facilities at Aalborg University (4)
• Portable equipment– 2.5m x 3.5m – Portable projector and PC– Passive stereo– 30 persons +
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Cases selected for VR presentation in the project
1. 3D airflow in a laboratory set-up with an isothermal slot inlet
2. Airflow and CO2-concentrations in a laboratory set-up with 4 wall inlets and “pig simulators”
3. Simulation of displacement ventilation in a room with closed pen partitions
4. Airflow in a similar room with a low momentum ceiling inlet
5. Airflow in a room with a radial inlet device
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Inlet
Outlet
Y
2.98m2.80m
1.00m
0.20m0.40m
X
Z
Y´
0´ X´
Z´
a
3.00m
5.00m
0
8.50m
Inlet flap
Inlet wall
Case 1
3D airflow in a laboratory set-up with an isothermal slot inlet
Air inlet
Air exhaust
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Air velocity at different z-positions during 13 hours (5 min average) - 4.5 m from inlet, 0.2 m below ceiling - the flow changes occasionally between two semi-stable conditions - values seem to be mirrored between z = 0.5 m and z = 4.5 m
0
0.2
0.4
0.6
0.8
1
Ve
locity,
m/s
0 200 400 600 800 Time, minutes
z=4.5mz=0.5mz=2.5m
Measured at 0.2m from ceiling & x=4.5m
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Case 2
Airflow and CO2 concentration in a laboratory set-up with 4 wall inlets and “pig simulators”
Air inlet
Air exhaust
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Case 3 – 4
Low momentum airflow in a room with closed pen partitions
Air inlet
Air exhaust
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Case 5
Airflow in a room with a radial inlet device
Air inlet
Air exhaust
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Methods of flow visualisation
• The presenter could scale and position the model in the 3D environment
• He could drag filled contour planes and vector planes arbitrarily through the model
• In addition he could place or drag seed points for streamlines or animated particle tracks in an intuitive way by moving physically around in the model
KJELD SVIDT, AALBORG UNIVERSITY
it.civil.auc.dk
Results and Conclusions
The VR facilities proved to be very efficient to visualise the three-dimensional airflow for people with no special background in 3D modelling and fluid motion
Especially the CAVE gave a very persuasive experience of being inside a virtual room with a virtual airflow
It requires some experience to navigate in the models and to scale and position them in a suitable way in relation to the physical surroundings (the audience, the panorama screen, the walls of the CAVE etc.)