Researchers have identified some of the underlying physics that may explain how insects can so quickly recover from a stall in midflight -- unlike conventional fixed wing aircraft, where a stalled state often leads to a crash landing.
The left image represents a non-rotating wing in the presence of incident flow; it exhibits a stalled state. The right image, taken shortly after the onset of rotation (at 36 degrees), shows a stable, lift-generating flow structure.
The analysis, in which the researchers studied the flow around a rotating model wing, improves the understanding of how insects fly and informs the design of small flying robots built for intelligence gathering, surveillance, search-and-rescue, and other purposes. The work is described in the journal Physics of Fluids.
An insect such as a fruit fly hovers in the air by flapping its wings -- a complex motion akin to the freestyle stroke in swimming. The wing rotates in a single plane, and by varying the angle between the plane and its body, the insect can fly forward from a hovering position.
To simulate the basics of this action, Matthew Bross and colleagues at Lehigh University in Bethlehem, PA, studied how water flows around a rotating model wing consisting of a rectangular piece of acrylic that is twice as long as it is wide. The rotation axis is off to the side of the wing and parallel to its width, so that it rotates like half of an airplane propeller. To simulate forward motion -- a scenario in which the insect is accelerating or climbing -- the researchers pumped water in the direction perpendicular to the plane of rotation.
"We were able to identify the development of flow structure over an insect-scaled wing over a range of forward flight velocities," Bross explained. The researchers made detailed three-dimensional computer visualizations of the flow around the wing, finding that a leading-edge vortex -- a feature crucial for providing lift -- almost immediately appears once the wing starts to rotate after a stalled state.
The article, "Flow structure on a rotating wing: effect of steady incident flow," by Matthew Bross, Cem Alper Ozen and Donald Rockwell appears in the journal Physics of Fluids. See: http://dx.doi.org/10.1063/1.4816632
Jason Socrates Bardi | Newswise
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences