Even though they are inanimate objects, sand dunes can “communicate” with each other.
The team found that the dunes interacted as they moved and drove their neighbors downstream.
Using an experimental “hiking trail for dunes”, the researchers found that two identical dunes began to be close to each other, but continued to move away from time to time. This interaction is controlled by the turbulent vortex of the upper sand dunes which push downstream. Sand dunes can communicate with each other.
Results reported. The key to researching long-term dune migration is that it threatens shipping channels, increases desertification, and can bury infrastructure such as roads.
When a pile of sand is exposed to the wind or a current of water, it forms a dune and starts moving downstream.
Sand dunes, whether on a desert, riverbed, or on the seabed, rarely appear in isolation and instead occur in large groups that form striking patterns known as dune fields or corridors.
Active sand dunes are known to migrate. In general, the speed of a dune is the opposite of its size: smaller dunes move faster and larger dunes move slower. Sand dunes can communicate with each other.
“There are different theories about interacting with sand dunes: One of them is that sand dunes of different sizes collide and continue to collide until they form giant mounds, even though this phenomenon has not been observed in nature.
Another theory is that dunes can collide and exchange mass, similar to billiard balls that bounce off each other as long as they are the same size and move at the same speed. However, we must experimentally confirm these theories.
Now Batic and his colleagues at Cambridge have shown results that call into question this explanation.
Much of the work in modeling dune behavior has been done numerically, but Vriend and his laboratory members have designed and built unique experimental facilities to monitor their long-term behavior. Fire filled with water is often used to study the movement of sand dunes in a laboratory environment. However, the dune can only be observed until the end of the tank.
In contrast, Cambridge researchers built rounded gutters so the dunes could be watched for hours while the gutters rotated while high-speed cameras allowed them to track the flow of individual particles into the dune. Sand dunes can communicate with each other.
Both dunes begin with the same volume and shape. When the current starts to move through two dunes, they start moving.
Knowing that the speed of the mound is related to its height, we expect the two dunes to move at the same speed.
Initially, the front bumps moved faster than the rear bumps, but as the experiment progressed, the front bumps slowed because two dunes moved at almost the same speed.
The most important, however, is that the flow patterns between the two sand dunes are different: the flow is deflected by the front mound, causing “vortices” in the rear mound and pushing them out.
The front mound creates a turbulence pattern that we see in the rear mound.
The flow pattern behind the front mound is like getting up behind the boat and affecting the property of the next mound.
In further experiments, the dunes move away and apart until they are in balance on the opposite side of the circular channel at a distance of 180 degrees. The next step in this research is to use quantitative observations and satellite imagery to find quantitative evidence for the migration of large and complex desert dunes. Sand dunes can communicate with each other.
By monitoring the accumulation of dunes over a long period of time, we can observe whether the steps to direct the migration of dunes are effective or not.