Initial studies on Virtual Reality Visualisation of 3D airflow in ventilated livestock buildings

KJELD SVIDT, AALBORG UNIVERSITYIt.civil.auc.dk

Initial studies on Virtual Reality Visualisationof 3D airflow in ventilated livestock buildings

Kjeld SvidtAalborg University


Contents of my presentation

Background

Methods

Facilities

Cases

Results and conclusions


Background- the project

Research project: “Control of Air Movement in Livestock Buildings” (1995-2001)

... 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


Background- 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 (CFD)


Background- why VR in this particular project

• Because it is possible• And because we see some possibilities in it• A pilot project to investigate the possibilities

Are we here ?

Or are we here ?


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 converted and displayed with the visualisation code VU (www.cerca.umontreal.ca/vu).

The results were displayed with active stereo in the panorama as well as the six-sided CAVE.


What is VR ?

Presentations that take place at the VR-Centre ?

Convincing your senses that something virtual is real

Making a realistic visualisation of something that is difficult to see in reality (e.g. airflow)

May include the following elements:

• Stereo viewing• A certain degree of immersion• Realtime interaction with the model/database• Tracking of persons or interaction device


VR facilities at Aalborg University (1)

Onyx2 IR2LightwaveMatrix-Hub

Cave

Panorama

3D Auditorium



• Panorama– Ø 7.1m, 160°, H 3.5m– Mono & aktive stereo– 28 persons– Tracking



• 6-sided CAVE– 2.5m x 2.5m x 2.5m– Back projektion– Aktive stereo– 1 person with tracking,

+ a few observers without tracking


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


Case 1. 2D visualisation of 3D flow

Air inlet

Air exhaust


Case 1

3D airflow in a laboratory set-up with an isothermal slot inlet

Air inlet

Air exhaust

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 2

Airflow and CO2 concentration in a laboratory set-up with 4 wall inlets and “pig simulators”

Air inlet

Air exhaust


Case 3 – 4

Airflow in a room with closed pen partitions

Air inlet

Air exhaust


Case 5

Airflow in a room with a radial inlet device

Air inlet

Air exhaust


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


Results and Conclusions (1)

• 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


Results and Conclusions (2)

• It requires some training 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.)

• In general we saw that inexperienced persons tend to stay in a fixed position trying to reach to the extents of the model instead of moving freely around in the available space.


Links

The project homepageiee.civil.auc.dk/i6/klima/projects/livestock

VR Media Lab, Aalborgwww.vrmedialab.dk/

IT in civil engineering at Aalborg Universityit.civil.auc.dk

Indoor Environmental Engineering at Aalborg Universityiee.civil.auc.dk

Center for AgroTechnology - Aalborg Universitycjt.auc.dk

Documents

Initial studies on Virtual Reality Visualisation of 3D airflow in ventilated livestock buildings