In landlocked South Dakota, hundreds of miles and 1,600 feet of elevation from the nearest ocean, South Dakota State University professor Francis Ting studies the structure of breaking waves like those that pound the world’s coastlines.
It’s not as odd as it sounds, given the fact that Ting worked previously as a postdoctoral research fellow at the University of Delaware Center for Applied Coastal Research.
“You see this wave breaking at the beach, and you just fall in love with it,” Ting said.
South Dakota offers few opportunities to study breaking waves at the beach, so Ting makes his own in the lab. He uses a 92-foot flume in the SDSU College of Engineering Fluid Mechanics Laboratory. The flume is a Plexiglas tank equipped with a computer-controlled wave maker. A measurement system consisting of a laser and two cameras captures the fluid motion produced by the waves as they break on a sloping bottom.
“A plane slope is the first step toward mimicking a beach in nature, although in this case it doesn’t have sediment,” Ting said. “That makes it easier to study the motion of the fluid without worrying about the sediment-transport aspects of it.”
Just as stormy conditions in the atmosphere sometimes produce the energetic local structures known as tornadoes, Ting said, breaking waves, too, have structure.
“The turbulence generated by the breaking waves has structure to it like a tornado in a storm,” Ting said. “The objective of the research is to identify the structures, what do they look like, how strong is the velocity, how big are these structures, and how long do they last — their temporal extent. Currently there’s very limited information on what is the flow structure produced as the wave breaks.”
With the help of a grant of $214,628 from the National Science Foundation, Ting, in SDSU’s Department of Civil and Environmental Engineering, has carried out extensive studies to try to answer those questions. The first step was to study a single wave.
“We found that the dominant structure consists of a downburst of turbulence. It’s quite logical. The wave impinges on the water surface as it breaks and then the jet of the breaking wave continues to move downward toward the bottom like someone pouring water into a pond.”
However, the downburst doesn’t just stay in the form of a jet of fluid but bends and rotates and creates vortices. Each downburst consisted of a core of downward flow accompanied by two spiraling flows, or vortices, that rotate in opposite directions to each other.
From measurements Ting and his students were able to identify the spacing of these structures and determine approximately how often they are generated.
From a single wave they moved on to study a periodic wave that consists of many identical waves breaking one after another. Ting said it’s important to study a wave train because it produces two effects that don’t occur with a single wave — the interaction of structures from successive waves, and the current known as the undertow. That current sometimes forces the flow structures within waves to change positions, Ting said.
Ting’s study found there are important differences in how two different types of breaking waves responded to the undertow. In plunging waves, like those with the curled crests that surfers ride, downbursts could overcome the effect of the undertow and carry turbulence onshore.
But in spilling waves — those in which the wave crest becomes unstable and water begins to fall down the front of the wave like a landslide — downbursts were quickly carried offshore by the undertow.
Ting said these findings are consistent with what coastal engineers have observed: that plunging waves tend to build up beaches, while spilling waves tend to tear them down.
“The detailed mechanism still has to be determined. It hasn’t been determined yet,” Ting said.
Ting said the logical next step would be to carry out similar experiments that include sediment to determine exactly how different types of breaking waves transport sediment. The work could lead to tools — in this case, computer models — that would help civil engineers and coastal managers better understand the different scenarios in which waves breaking on beaches erode or deposit sediments.
Ting needs additional instruments that can measure sediment transport before he can carry out that work. He’s pursuing funding to get that equipment and carry out those experiments.
Ironically, Ting is building South Dakota State University’s reputation in the meantime as the source of some important research that could find applications such as protecting beachfront property — not exactly the sort of thing for which South Dakota scientists are best known.
Ting’s lab was established with funding from the National Science Foundation, the Office of Naval Research, and South Dakota EPSCoR, the Experimental Program to Stimulate Competitive Research.An oral presentation and computer animations of his laboratory measurements can be viewed at
Jeanne Jones Manzer | Newswise Science News
GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center
Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy