Scientists hope to mimic the most extreme hurricane conditions

 The efforts need to reproduce the havoc wreaked by both wind and water

Hurricane Irma makes landfall in the United States on September 10, 2017, bringing high winds and flooding to Miami.
Hurricane Irma makes landfall in the United States on September 10, 2017, bringing high winds and flooding to Miami.



Winds above 300 kilometers per hour battered a two-story timber house, ripping the roof from the walls and ripping the roof from the walls. After that, there's the water. The structure is engulfed by a 6-meter-high wave, which knocks the house off its base and washes it away.

Researchers planning a new state-of-the-art facility to re-create the devastation inflicted by the world's most destructive hurricanes have a horrifying vision. Researchers were awarded a $12.8 million grant by the National Science Foundation in January to design a facility that can imitate wind speeds of at least 290 km/h while also producing catastrophic, towering storm surges.

There is no facility that can produce such a powerful combination of extreme wind and water. But it's an idea whose time has come — and it couldn't have come at a better time.

Disaster researcher Richard Olson, director of severe events research at Florida International University in Miami, says, "It's a race against time."

Hurricanes are becoming bigger, wetter, stronger, and slower as a result of human-caused climate change (SN: 9/13/18; SN: 11/11/20). The 2022 Atlantic Ocean hurricane season, which runs from June 1 to November 30, is expected to be the seventh consecutive season with more storms than average, according to scientists. Hurricanes have been rapidly intensifying in recent seasons, which has been related to warming ocean waters (SN: 12/21/20).

According to academics, these tendencies are predicted to continue as the Earth warms even more. And coastal cities all around the world need to know how to prepare: how to create structures that can withstand such strong winds and waves, such as buildings, bridges, roads, water, and energy systems.

FIU academics are leading a team of wind and structural engineers, coastal and ocean engineers, computer modelers, and resilience experts from all over the country to figure out how to best replicate these behemoths. According to Ioannis Zisis, a wind engineer at FIU, combining strong wind and water surges into one facility is unexplored ground. "It's important to push the boundaries," Zisis says. But, when it comes to how to go about doing it, "the answer is simple: We don't know." That's what we're looking for."

Prepping for “Category 6”

It's not as though such violent storms haven't occurred before on Earth. Hurricanes Dorian (2019) and Irma (2017) in the Atlantic Ocean, as well as super Typhoon Haiyan (2013) in the Pacific Ocean, have all recently brought storms with wind speeds above 290 km/h. Though it isn't an official title, such severe storms are commonly referred to as "category 6" hurricanes.

Hurricanes in the Atlantic and eastern Pacific oceans are rated on a scale of 1 to 5 by the National Oceanic and Atmospheric Administration, or NOAA, based on their wind speeds and potential damage. Each category is divided into 30 km/h increments.

With wind speeds of 119 to 153 km/h, Category 1 storms cause "some damage," such as bringing down power lines, falling trees, and possibly ripping roof tiles or vinyl siding off a house. Catastrophic damage is caused by Category 5 storms, which have gusts of up to 252 km/h and can bulldoze buildings and make areas uninhabitable for weeks or months.

But, on the official scale, a 5 is the maximum; after all, what could be more terrible than catastrophic damage? Even monster storms like Hurricane Dorian, which destroyed the Bahamas in 2019 with wind gusts of around 300 km/h, are still classified as category 5 (SN: 9/3/19).

"Strictly speaking," Olson continues, "I understand that [NOAA] does not see the need for a category 6." He claims, however, that there is a difference in public perception. "I see it as a different kind of storm, one that is simply more terrifying."

And, labels aside, the necessity to prepare for these more powerful storms is obvious, according to Olson. "I don't think anyone wants to be explaining why we didn't do this in 20 years," he says. "We've put nature to the test." "Welcome to retaliation."

FIU already has the Wall of Wind, a big storm simulator situated in a vast hangar with an arc of 12 massive yellow fans anchored at one end. The fans produce a loud, disturbing hum even at moderate wind speeds — say, approximately 50 km/h. Those fans can generate wind speeds of up to 252 km/h at full blast, which is equivalent to a low-grade category 5 hurricane.

Inside the hangar, researchers build structures that resemble skyscrapers, houses, and trees, as well as shapes that simulate bumps and dips in the ground surface. Engineers from all over the world come to the facility to test the wind resistance of their own designs, watching as the winds wreak havoc on their structures.


Superstorm simulation

The Wall of Wind, a big storm simulator situated in a large hangar with an arc of 12 massive yellow fans anchored at one end, is already on the premises of FIU. The fans produce a loud, disturbing hum even at moderate wind speeds, such as around 50 km/h. Those fans can generate wind speeds of up to 252 km/h, which is equivalent to a low-grade category 5 hurricane when they are turned on full blast.

Inside the hangar, researchers build structures that resemble skyscrapers, houses, and trees, as well as shapes that resemble bumps and dips in the earth's surface. Engineers from all over the world come to the site to test the wind resistance of their own inventions, watching as the winds batter them.

It's one of eight facilities that make up the U.S. Natural Hazards Engineering Research Infrastructure, or NHERI, a national network of laboratories that research the effects of wind, water, and earthquake hazards.

The Wall of Wind is a wind tunnel that may be used to test complete constructions at full scale. Another wind machine, located at the University of Florida in Gainesville, can zoom in on turbulent wind behavior directly at the atmosphere-ground boundary. Then there are the massive water wave tanks at Oregon State University in Corvallis that simulate tsunamis and storm surges.

The new facility will stand on the shoulders of these titans, as well as other experimental labs across the country. The design phase is expected to take four years, as the team considers how to increase wind speeds — perhaps with more or more powerful fans than the Wall of Wind's — and how to combine gale-force winds and enormous water tanks in a single experimental environment.

Existing labs that research wind and waves together, albeit on a much smaller size, can provide some insight into that part of the design, according to Forrest Masters, a wind engineer and the director of the University of Florida's NHERI facility.

As part of the design phase, a scaled-down prototype of the future lab will be built as a proof of concept. A new round of funding and several additional years will be required to complete the full-scale facility.

Making field observations of the aftermath of a given storm, building experimental facilities to re-create storms, and using computational simulations to visualize how those impacts might play out over large geographical regions have all been used in the past to study the impacts of strong wind storms. According to Tracy Kijewski-Correa, a catastrophe risk engineer at the University of Notre Dame in Indiana, each of these approaches has advantages and disadvantages.

"We want to put all of these techniques together in this facility," Kijewski-Correa says, "to get as near as possible to reproducing what Mother Nature can achieve."

It's a difficult technical problem, but one that's also intriguing. "In the broader scientific community, there's a lot of enthusiasm for this," Masters says. "Nothing like it will exist if it is built."

CITATIONS
A. Chowdhury et al. Natural hazards engineering research infrastructure (NHERI): Mitigating the impact of natural hazards on civil infrastructure and communities. Frontiers in Built Environment. Published online June 15, 2021. DOI: 10.3389/fbuil.2021.708450.


------- -------
Comments
No comments
Post a Comment



    Reading Mode :
    Font Size
    +
    16
    -
    lines height
    +
    2
    -