Professor Mark Sterling's Adventures in Fluid Mechanics

Posted on Monday 10th February 2014

Following his Inaugural Lecture, Ros Dodd met Professor Mark Sterling to find out more about the major impact of Birmingham's research into Fluid Mechanics.

Food prices may have soared in the past few years, but we are paying less for our bread and cereals than we might have done had Professor Mark Sterling not worked out how to prevent crops from falling over in high winds!

Mark was part of a team that examined the structure of wheat to see what could be done to stop it being battered to the ground in bad weather.

As a result, agronomists and biologists were able to change certain traits in the crop plant – making it shorter and its roots wider – to make it more robust. 

Now Mark, Beale Professor of Civil Engineering and Head of the School of Civil Engineering, is turning his attention to trying to stop buildings collapsing in extreme weather such as tornados.

That he loves what he does is evident from the title of his recent Inaugural Lecture: ‘Adventures in fluid mechanics (aka getting paid to play).’

‘I really enjoy it – it’s a lot of fun,’ he enthuses. ‘Many people say academia has changed so much over the last few years that they wouldn’t go into it if they had their time again. But I still would: It provides the freedom and intellectual challenge that you don’t get elsewhere. Obtaining funding for research can be incredibly frustrating, but it also makes you think carefully about the quality of the proposals you put forward.’

His only regret is that since becoming Head of School two years ago, he’s had less time to devote to his research: Spanning fluid dynamics, wind engineering and water engineering, Mark’s work has won more than £3 million in funding and is internationally renowned. 

So what led him towards trying to tame the effects of wind and water?

Mark says that at university in Nottingham, where he did a degree in Civil Engineering, he ‘really enjoyed the fluid mechanics aspect’ and his tutors suggested going to Birmingham because of the University’s reputation in water engineering.

‘Donald Knight, now Emeritus Professor and a legend in his field, offered me a place as a PhD student and I never really looked back.’

Apart, that is, for a brief stint in industry. ‘I decided I wanted to earn lots of money, so left academia to become an IT consultant,’ recalls Mark. ‘I lasted about a year – it was incredibly boring and I missed my life in academia. So I returned to the University, where I’ve been ever since.’

It was then that Mark turned his attention to wind, under the guidance of Prof Chris Baker, Professor of Environmental Fluid Mechanics at Birmingham and a former lecturer of Mark’s at Nottingham.

‘I started worrying about crops falling over,’ he says with a smile. ‘On the face of it, this is as far removed from civil engineering as you could possibly get, but in fact crops are just very dynamic structures that move in the wind – as opposed to buildings that shouldn’t move very much. 

‘The thing about buildings is that they are quite regular, whereas the property of a crop can vary significantly within a couple of metres.’

Mark’s first wind experiment involved building the first-ever portable wind tunnel and spending ‘three glorious summers standing in a field in Herefordshire getting a suntan while pretending to do some hard scientific research’!

Fun it might have been, but it yielded valuable results. ‘It enabled us to calibrate a numerical model that we were able to give to agronomists and biologists to tell them which traits of a plant needed to change to stop it falling over. In a nutshell, if you’re able to alter a plant’s natural frequency, and that’s related in part to its height, and if you’re able to alter the structure of its roots, then you can stop it falling over.’

At the time, this was a real problem: In 1992, for example, the UK economy lost about £130m in crop yield due to plants being blown to the ground and ruined.

‘Ultimately, because we’ve stopped wheat blowing over, we’ve saved the industry money, so your bread and cereal aren’t as expensive as they would have been.’

Mark and his team have since helped the Argentinians modify their sunflowers to stop them toppling over. More recently, he has turned his attention to barley and, now, oats. ‘We’ve started to look at oats, but the structure of the crop is a lot different.’

As well as crops, Mark’s wind engineering research also focuses on ways to prevent buildings from falling down in exceptional wind conditions such as thunderstorms and tornados.

‘What brings it all together – wind and water – is trying to understand the swirling motions – or eddies – within a fluid, whether that’s water or air, and how those eddies impact on, for example, cereal crops, vehicles such as cars and trains, as well as on buildings.’

His work involves looking at the effect of non-stationary or transient winds, where speed and direction differ from ‘ordinary’ strong winds. To understand more about how these kinds of wind affect how, say, a building can withstand a tornado, Mark and his team are building a large-scale transient wind generator in the lab.

‘There are already large-scale generators in Texas and Canada, but when you do things on different scales, you never quite know how much is scale-affected,’ says Mark. ‘Although ours will be large, it will be a different scale from the Americans’ generator. If our results are totally different, then we’ll know that we as a scientific community need to rethink our approach. But if we get similar results, then we could be on the road to designing buildings more efficiently in the face of extreme winds.’

For further information please contact Samantha Williams, Communications Officer for the College of Engineering and Physical Sciences