The Centre for Wind, Waves and Water 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:
Boundary Layer Wind Tunnel
The Boundary Layer Wind Tunnel is a new state-of-art facility in the School of Civil Engineering that will contribute to the university’s research portfolio in atmospheric flows.
The wind tunnel was designed to conduct boundary layer experiments for the study dispersion in urban flows, wind loads on buildings, wind energy, fluid-structure interaction, and atmospheric turbulence. The tunnel is available for research, consulting and teaching activities.
Featuring an impressive boundary layer section of 20m x 2.5m x 2 m (l x w x h), the wind tunnel is one of very few facilities in Australia capable of measuring high Reynolds number flows. The tunnel can generate flow velocities up to 100 kmph (62 mph) and fit relatively large scale-models over its 2.5m diameter turn table. 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.
Wind Tunnel instrumentation
A number of different instruments are used for measuring and understanding the behaviour of wind in wind tunnel experiments. These include:
- Particle Image Velocimetry
- High frequency pressure scanning system
Up to 512 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.
- 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 probes
Used for quick and accurate velocity profile measurements, the robust and easy use of this instrument makes it invaluable to our thunderstorm downburst research.
- Flow Visualisation
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.