sand dunes
Scientists at Thailand’s Nakhon Phanom University and New Zealand’s University of Otago are helping coastline management in New Zealand with research investigating wind flow over sand dunes.

The coastal area near Dunedin, New Zealand, constantly suffers from erosion. It is characterised by a ‘harsh’ land-sea interface consisting of extremely high, steep sand dunes. The erosion can be both hazardous – parts of the beach have to be closed off to the general public – and expensive for the local authorities, as lost sand must be constantly replaced. The Dunedin City Council (DCC) are therefore keen to develop new management strategies that deal with the problem effectively.

Wichai Pattanapol, a researcher at Nakhon Phanom University and his colleagues investigated the reasons behind Dunedin’s erosion problem using Computational Fluid Dynamics (CFD). Generally this technique uses numerical methods and algorithms to study the effects of forces on liquids and gases, including air. They used computer generated simulations to model different patterns of movement and energy for wind and windblown sand over the sand dunes.

Computational fluid dynamics (CFD) simulation

Computational fluid dynamics (CFD) simulation of windblown sand over a sand dune. © Dr Wichai Pattanapol

“The simulations showed the pattern of flow over different modified topography scenarios,” explains Wichai, “The results suggest the DCC should introduce a ‘soft’ land-sea interface, by making the front slope less steep. This will dramatically reduce the energy of wind at the land-sea interface.” The research shows that CFD, which is normally used in industrial sectors, for example measuring air flow over racing cars or inside buildings, can be applied to complex environmental issues.

Dr Pattanapol warns that numerical simulations of this nature are rarely “error-free”, but explains that the simulations have since been verified by laboratory and field studies. “I believe the DCC are taking our recommendation seriously,” he said.

The research team and the DCC have organised a meeting with local people to explain to them about the upcoming topography modification, and its effect on wind patterns.

For further information contact:

Dr Wichai Pattanapol
Nakhon Phanom University, Thailand
Dr Sarah Wakes
University of Otago, New Zealand