The Wind, Waves and Water Centre participates in the continuing update and development of the facilities within the Fluids Laboratory of the School of Civil Engineering. The facilities at the service of the centre are:
The centre conducts research in wind engineering in two wind tunnels:
Boundary Layer Wind Tunnel
Test section: 2.0 m x 2.4 m; fetch: 20 m
Maximum wind speed: 16 m/sec in the boundary layer section
The Boundary Layer Wind Tunnel is an open circuit wind tunnel used within the department for research, consulting and teaching activities. The atmospheric boundary layer test section is uniquely suited for the study of wind induced building pressures, building motion and pedestrian wind climates. The blockage tolerant section also allows detailed assessment of complex topographic areas (e.g. analysis of wind turbine placement). The tunnel is equipped with variable levels of fetch roughness so site specific turbulence characteristics can be simulated.
Snowdrift Wind Tunnel
Test section: 0.6 m x 0.9 m; fetch: 4 m
Maximum wind speed: 6 m/sec
The Snowdrift Wind Tunnel is a closed circuit wind tunnel with sodium bicarbonate (baking soda) used for snow simulation. The snowdrift wind tunnel can be used to model wind driven snow deposition patterns around simple and complex structures giving temporal and spatial prediction of snowdrift patterns. Sodium bicarbonate is used for scaled snow particles due to its density, compaction and angle of repose properties. The snowdrift wind tunnel is used for research and consulting activities and has been used in modelling drift patterns in the Southern Alps region of Australia, and Antarctica.
Wind Tunnel instrumentation
A number of different instruments are used for measuring and understanding the behaviour of wind in wind tunnel experiments. The Wind, Waves and Water Centre instrumentation includes:
- Particle Image Velocimetry
- High frequency pressure scanning system
Up to 256 pressure taps can be simultaneously scanned for measuring façade cladding pressures or for integrating pressures over the face of a structure.
- High frequency base balance
This is used for determining overall structural loads applied to a building's foundations or supports. Knowledge of the dynamic properties of a building allows a prediction of structural responses.
- Aero-elastic strain gauge systems
This is used for highly wind sensitive structures where mode shape predictions are not adequate and structural response must be measured by fully modelling a building’s structural characteristic.
- Constant Temperature Anemometry (hot-wires)
This is used to measure the wind velocity at different locations in the wind tunnel. The miniature size and multi-directionality of hot-wires makes them ideal for pedestrian/environmental comfort testing.
- Cobra probe
Used for quick and accurate velocity profile measurements, the robust and easy use of this instrument makes it invaluable to our thunderstorm downburst research.
The Fluids Laboratory is an innovative facility to study the dynamics of suspended particle matter in water. The laboratory consists of a column 60 cm high and a 16 x 16 cm base in which sediment is mixed with an oscillating grid, which allows control of the turbulence shear rate. Sediment concentration and oscillation frequency can be controlled, as well as the temperature. The column can be used with non-cohesive and cohesive particles, and with mineral and organic compounds.
The bottom of the column consists of a measuring section in which sediment settles through a small orifice on a diaphragm that separates the mixing control volume from the measuring section. In the measuring section, a micro-PIV system is used to take optical images of particles and to study several geometrical and physical variables.
The facility is being used to study:
- Flocculation of suspended particle matter
- Sedimentation processes
- Particle removal
- The interaction between sediment, microorganisms and water
- Aquatic biogeochemistry
The Fluid Laboratory has a range of water tanks for conducting experiments on various research projects. Most of these tanks are made of transparent Perspex sheets of varying thickness with copper plates as heating or cooling surfaces. The transparent surfaces allow light to pass through so that flow visualization experiments can be carried out.
Rectangular and square tanks
Typical tanks in this group have two copper plates on two opposing surfaces, and the rest of the surfaces are made of Perspex sheets. Heating and/or cooling chambers are attached to the model tank through the copper plates.
These tanks are designed primarily for conducting vertical natural convection boundary layer and heat transfer experiments. Both transient and steady state experiments can be carried out with these tanks. The particular tank shown in Figure 1 is 1-m long, 0.24-m high, and 0.5-m wide. It also has two pneumatically-operated gates, one on each side, for start-up experiments. For the start-up experiments, the gates are initially at their resting positions so that the hot and cold water in the buffer tanks is separated from the copper plates (sidewalls) by air gaps. At the start-up, the gates are lifted up (Figure 2) within a fraction of a second so that the hot and cold water in the buffer tanks flushes against the respective sidewalls to initiate heating and cooling. An approximately instantaneous start-up can be achieved with this setup.
The smaller versions of rectangular/square tanks can be easily rotated for conducting other experiments such as Rayleigh-Benard experiments (heating from the bottom and cooling from the top) and pure conduction experiments (heating from the top and cooling from the bottom).
Triangular and wedge-shaped tanks
These tanks are designed for modelling natural convection induced circulation in coastal waters. There are two typical configurations of these tanks, one with a sloping bottom and either free or rigid surface, and the other with a sloping bottom connected with a flat bottom, and again with either free or rigid surface. Schematics of these two configurations are shown in Figure 3.
The scale of these tanks goes from 300 mm up to 2 m in length. With the free surface configuration, lighting can be applied from the top to model radiative heating of the water body. The rigid surface configuration has a copper plate on the top surface, and is designed for temperature controlled heating and cooling experiments, in which hot or cold water is circulated through the chamber sitting above the rigid surface.