The Secrets of a Bug's Flight

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New experiments in Pennsylvania, described in the journal "Physics of Fluids," offer insight into how insects fly and how to design tiny flying robots

From the Journal: 

WASHINGTON, D.C. Nov. 12, 2013 -- 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 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.

Wings and rotation

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.

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For More Information:
Jason Socrates Bardi 
jbardi [at] aip.org
 
240-535-4954
 
@jasonbardi

Article title: 
Authors: 
Matthew Bross, Cem Alper Ozen and Donald Rockwell
Author affiliations: 
Lehigh University in Bethlehem, PA
About the journal: 

Physics of Fluids

Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids.