My Space: feeling the force at the University's wind tunnel

The University’s wind tunnel looks unassuming: a plain white corridor, about 24 metres long, with large fans at one end and two mesh screens at the other.

But once the wind kicks in, the tunnel doesn’t feel so meek.

The largest of its kind in New Zealand, the Boundary Layer Wind Tunnel can blow at a roaring 18.9 metres per second, or 68 kilometres an hour.

For context, should you find yourself in the tunnel with the fans at full force and when they’re testing a model car (about the size of a coffee table), the vehicle would fly at you like a projectile.  

Of course, Dr Ahmad Zaki wouldn’t allow that to happen; no one is allowed to enter the wind tunnel while object testing is underway, for obvious health and safety reasons.

Ahmad has spent almost a decade here, first as a PhD student researching turbulent flows and, for the past five years, as the senior lab technician, overseeing the Aerodynamics Laboratory, which houses the wind tunnel.

He tends to its specialised equipment, helps build the models that are tested in it, and provides technical advice for the researchers and students who use the space for experiments. Lead technologist Dr Young Min Shim manages the tunnel’s commercial and industrial activity.

The tunnel’s test section, between the fans and screens, is split in three sections: a bike rig for measuring the drag on cyclists and athletes, a rolling road for testing model vehicles, and a large turntable for testing building resilience under certain conditions.

On any given day, Ahmad might be helping students and researchers test bluff bodies – that’s any object that interacts with wind – against controlled or chaotic wind conditions. He also flies drones and UAVs, with a motion-capture system inside the tunnel simulating a GPS.

The scale of the tunnel means it can handle a variety of projects, and Ahmad says there are only a small number of such facilities globally.

“It’s cool to see the different projects and preparations that happen here, and I enjoy having the freedom to create and build what I need to improve the lab.”  

Three years ago, he helped the Mechanical and Mechatronics Student Association host a kite-flying competition. The kites were fixed into the tunnel’s floor, and judges assessed the kites’ design, durability and flight, testing which of the students’ designs could best survive the strongest wind forces.

These days, he’s helping a pair of fourth year masters students on exchange from France test an airfoil – a small slice of an airplane wing, scaled down for testing.

The wind tunnel’s closed-loop design continuously circulates air, using less energy than designs that need to constantly regenerate airflow. Its boundary layer setup allows researchers to mimic how wind behaves near the ground: slower and more resistant close to the surface, and faster as it rises.

Think of it like honey on a plate, says Ahmad.

“Tilt it, and the lower layers of the honey will stick, while the upper layer starts to slide. The same happens with wind, but it’s just not visible,” he says.

To create real-world turbulence, the students testing the airfoil have placed a large flag in the test section. When the wind picks up, the flag flickers unpredictably, producing the kind of chaotic flow an airfoil might encounter outdoors.

“Turbulence is measurable, but we want it to fluctuate randomly to simulate real-life conditions, because there is randomness in real life,” says Ahmad.

“The wind tunnel helps us understand that randomness in a controlled way.”

– Jogai Bhatt