Lead Flapping Objects Experience Less Wind Resistance Than Their Trailing Counterparts, NYU and Cornell Researchers Find


Their study, published in the most recent issue of the journal Physical Review Letters, discovered that in a series of flags, the leading flag faces significantly less resistance than do succeeding flags. The finding may alter our understanding of how living flapping creatures, such as birds or fish, move through the air and water.

An overhead view of a pair of tandem flags flapping in a downward flowing soap film.
An overhead view of a pair of tandem flags flapping in a downward flowing soap film.

It is commonly known that racing cars and bicyclists can reduce air resistance by following closely behind a leader, but researchers from New York University and Cornell University have found the opposite is true with flapping objects, such as flags. Their study, published in the most recent issue of the journal Physical Review Letters, discovered that in a series of flags, the leading flag faces significantly less resistance than do succeeding flags. The finding may alter our understanding of how living flapping creatures, such as birds or fish, move through the air and water.

“Inspired by schooling fish and flocking birds, we studied how flapping flags alter fluid drag forces, or resistance that moving objects face, on one another when grouped together,” said Jun Zhang, an associate professor in NYU’s Physics Department and its Courant Institute of Mathematical Sciences and a co-author of the study. “To our surprise, we discovered that the leading flag enjoys a drag reduction of up to 50 percent while its downstream neighbor suffers a significant drag increase. If this effect applies to fish schools 500

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