THE BLOG

Post-Haiyan, a New Paradigm Is Needed to Prepare for Storms of the Future

11/11/2013 17:20 | Updated 23 January 2014

This article is co-authored with Professor Horia Hagan who is Director of the WindEEE Research Institute at Western University Canada.

Haiyan was the 25th typhoon to enter Philippine territory this year. It has caused havoc and, worryingly, it will be unclear for some time what the precise scale of loss of life in the country is. However, the death toll is reported to be at least 10,000 in the province of Leyte alone.

Power and communications were widely lost in the country. There has also been massive structural damage, including collapsed homes and buildings.

Remarkably, winds were reported of over 200 mph (more than 300 km/h), bringing up to 400 millimetres (15.75 inches) of rain in some places, and waves of some 15 metres (45 feet). Indeed, it is possible that Haiyan could be the strongest ever tropical storm to make landfall.

Unfortunately, Asia, and much of the rest of the world, is likely to face increased intensity, hurricane force winds with changing trajectories - a consequence of climate change - which can lead to more storms in some countries. This includes Vietnam (where Haiyan has also made landfall) where typhoons penetrate further inland.

As well as causing the average intensity of storms to increase - which means stronger winds - global warming will result in a rise in rainfall rates in storm centres too. Total rainfall will also probably grow when big storms hit land. We know already that the frequency of heavy rain events, as well as rainfall intensity (amount of rain per unit of time) has increased.

These disturbing facts mean that we need nothing less than a new approach to wind engineering to prepare for storms of the future. To this end, approximately 100 researchers from across the world gathered at Western University, Canada last month to explore new frontiers of wind engineering, energy and the environment.

A key challenge is that traditional wind tunnels widely used today for science and testing applications from planes to cars, buildings and air quality applications create uni-directional, and constant speed air flows. They simply cannot reproduce the complex space and time variation of localised wind storms that we are seeing increasing today. Moreover, due to their size and geometry, traditional wind tunnels are also not capable of reproducing all scales of wind motions involved in wind energy and wind environment studies.

However, a breakthrough is now emerging. The WindEEE Dome at Western University, Canada is a new 25 metre diameter wind testing chamber that attempts to address these shortcomings. The 3 E's stand for the applications: wind engineering (the damaging effect of wind on structures); wind energy (the positive effect of generating power out of wind); and wind environment (the way wind interacts with the natural and built habitat from forest canopies to city microclimates).

WindEEE's hexagonal chamber has 100 fans distributed on six walls and six more, larger fans, above the chamber. When coupled together, these 106 fans can re-create almost any type of wind system in a three-dimensional and time dependent manner. This is a crucial development if we are to meet the challenges posed by future storms.

For instance, by coupling the fans on the periphery and injecting air into the chamber at certain angles, one can create a twist, which, in conjunction with a negative pressure created by the fans above the chamber, generates a vortex. This vortex can simulate the eye of a hurricane, typhoon or an entire tornado for which field measurements now exist such as those on instrumented towers along the South China coast.

The storm fields can move through the chamber at rapid speeds (2 metres a second) reproducing the track of typhoons or tornadoes. Remarkably, every fan on the periphery can be actuated at 1 Hertz (i.e. the wind speed can be varied in 1 second) making the WindEEE Dome capable of actively reproducing atmospheric turbulence.

One of the many practical applications of WindEEE is that it can help us understand more about vulnerability to turbulence from the level of a community to the level of individual buildings and structures, including high-rise towers, so that we can develop better design codes. This is especially important given the number of buildings being constructed right across the world, especially in coastal areas and/or growing mega-cities.

Taken overall, it is clear that storms increasing have a space and time variability, non-uniformity, and much higher level complexity of wind, than traditional engineering has catered for. As Typhoon Haiyan reminds us, we must therefore adopt a new engineering approach to enable our preparedness.

WindEEE is a good example of exactly what is needed to make the necessary quantum leap forward in wind research. We must now encourage similar science and technological innovation to meet the challenges posed by storms of the future.