WhatsNew2Day
Latest News And Breaking Headlines

The sand dunes communicate & # 39; communicate creating turbulence that repel its neighbors downstream

The sand dunes & # 39; communicate & # 39; each other creating turbulence in its path, similar to that of moving boats, which repels its neighbors downstream.

Cambridge University experts built a circular tank that functions as a race track, allowing them to see the dunes migrate in the flowing water for long periods of time.

When two dunes came together on the race track, the researchers discovered that they were moving away more and more over time.

This separation increased until the dunes were on opposite sides of the track.

In addition, by using high-speed cameras to monitor individual particles that move through the dunes, the researchers found that the flow over each dune was different.

The finding is key to understanding the migration of dunes that can threaten shipping channels, increase desertification and even bury infrastructure, such as roads.

Scroll down to watch the video

The sand dunes & # 39; communicate & # 39; each other creating turbulence in its path, similar to that of moving boats, which repels its neighbors downstream.

The sand dunes & # 39; communicate & # 39; each other creating turbulence in its path, similar to that of moving boats, which repels its neighbors downstream.

"This interaction is controlled by turbulent swirls of the upstream dune, which push the dune downstream," said lead author of the article and applied mathematician Karol Bacik of the University of Cambridge.

The dunes form, and begin to move downstream, when the piles of sand are exposed to wind or water flow.

Whether in deserts, on river beds or at the bottom of the sea, sand dunes rarely occur in isolation, instead of appearing in large groups to form patterns known as dune fields or corridors.

Active sand dunes migrate at speeds that depend on their sizes, with smaller dunes that move faster and larger dunes that move more slowly.

Despite knowing that the dunes can move at different speeds, it was not clear how the dunes could interact with each other; For example, what would happen if one dune met another and they collided.

& # 39; There are different theories about the interaction of dunes. One is that dunes of different sizes will collide, and will continue to collide, until they form a giant dune, although this phenomenon has not yet been observed in nature & # 39; & # 39 ;, said Bacik.

"Another theory is that the dunes can collide and exchange mass, like billiard balls that bounce off each other, until they are the same size and move at the same speed," he added.

However, when they tried to test these competitive hypotheses, the researchers discovered that something completely different happens between the dunes.

"We've discovered physics that hasn't been part of the model before," said lead researcher and mechanical engineer Nathalie Vriend.

In general, research on the behavior of sand dunes has been done numerically.

However, for their study, the researchers built a unique experimental facility that allowed them to study the behavior of the dunes in the long term.

Water-filled tanks in which waves are generated are common tools for studying sand dunes that change shape in the laboratory, but normally dunes can only be monitored until they reach the end of the canal.

To circumvent this limitation, Bacik and his colleagues built a circular tank that acts as a racetrack, allowing the dunes to keep moving for hours as the canal rotates.

The researchers used high-speed cameras to track the flow of individual particles within the dunes.

"Originally, I put several dunes in the tank just to speed up data collection, but we didn't expect to see how they started interacting with each other," Bacik said.

When the experiment began, the two dunes had the same volume and the same shape, and began to move when the water began to flow.

"Since we know that the speed of a dune is related to its height, we expected the two dunes to move at the same speed," explained Dr. Vriend.

"However, this is not what we observe."

Bacik and his colleagues built a circular tank that acts as a race track, pictured, allowing the dunes to keep moving for hours while the canal rotates

Bacik and his colleagues built a circular tank that acts as a race track, pictured, allowing the dunes to keep moving for hours while the canal rotates

Bacik and his colleagues built a circular tank that acts as a race track, pictured, allowing the dunes to keep moving for hours while the canal rotates

At first, the front dune moved faster than the rear dune, but as the experiment continued, the researchers observed that the front dune slowed, until the two dunes moved at almost the same speed, on opposite sides of track.

The researchers discovered that the flow pattern through the two dunes was different, with the passage of disturbed water passing over the front dune, generating & # 39; swirls & # 39; in the rear dune and away.

"The front dune generates the turbulence pattern we see in the rear dune," explained Dr. Vriend.

"The flow structure behind the front dune is like a wake behind a boat and affects the properties of the next dune."

At first, the front dune moved faster than the rear dune, but as the experiment continued, the researchers observed that the front dune slowed, until the two dunes moved at almost the same speed, on opposite sides of The race track.

At first, the front dune moved faster than the rear dune, but as the experiment continued, the researchers observed that the front dune slowed, until the two dunes moved at almost the same speed, on opposite sides of The race track.

At first, the front dune moved faster than the rear dune, but as the experiment continued, the researchers observed that the front dune slowed, until the two dunes moved at almost the same speed, on opposite sides of The race track.

With its full initial study, the team now hopes to find evidence of similar large-scale and complex dune migrations in deserts, using field observations and satellite images.

This, they explained, will allow them to assess whether measures aimed at diverting the migration of the dunes are effective.

The full findings of the study were published in the journal. Physical Review Letters.

.