Delta-wing function of webbed feet gives hydrodynamic lift for swimming propulsion in birds
(2003) In Nature 423(6944). p.65-68- Abstract
- Most foot-propelled swimming birds sweep their webbed feet backwards in a curved path that lies in a plane aligned with the swimming direction. When the foot passes the most outward position, near the beginning of the power stroke, a tangent to the foot trajectory is parallel with the line of swimming and the foot web is perpendicular to it. But later in the stroke the foot takes an increasingly transverse direction, swinging towards the longitudinal axis of the body. Here we show that, early in the power stroke, propulsion is achieved mostly by hydrodynamic drag on the foot, whereas there is a gradual transition into lift-based propulsion later in the stroke. At the shift to lift mode, the attached vortices of the drag-based phase turn... (More)
- Most foot-propelled swimming birds sweep their webbed feet backwards in a curved path that lies in a plane aligned with the swimming direction. When the foot passes the most outward position, near the beginning of the power stroke, a tangent to the foot trajectory is parallel with the line of swimming and the foot web is perpendicular to it. But later in the stroke the foot takes an increasingly transverse direction, swinging towards the longitudinal axis of the body. Here we show that, early in the power stroke, propulsion is achieved mostly by hydrodynamic drag on the foot, whereas there is a gradual transition into lift-based propulsion later in the stroke. At the shift to lift mode, the attached vortices of the drag-based phase turn into a starting vortex, shed at the trailing edge, and into spiralling leading-edge vortices along the sides of the foot. Because of their delta shape, webbed feet can generate propulsive forces continuously through two successive modes, from drag at the beginning of the stroke, all the way through the transition to predominantly lift later in the stroke. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/951294
- author
- Johansson, Christoffer LU and Norberg, Åke
- publishing date
- 2003
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Nature
- volume
- 423
- issue
- 6944
- pages
- 65 - 68
- publisher
- Nature Publishing Group
- external identifiers
-
- scopus:0038264100
- pmid:12840759
- ISSN
- 0028-0836
- DOI
- 10.1038/nature01695
- language
- English
- LU publication?
- no
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical ecology (Closed 2011) (011006011)
- id
- 92293acd-9ef6-4b71-bfbd-5a13ffe0ce95 (old id 951294)
- date added to LUP
- 2016-04-01 12:23:05
- date last changed
- 2022-01-27 02:59:49
@article{92293acd-9ef6-4b71-bfbd-5a13ffe0ce95,
abstract = {{Most foot-propelled swimming birds sweep their webbed feet backwards in a curved path that lies in a plane aligned with the swimming direction. When the foot passes the most outward position, near the beginning of the power stroke, a tangent to the foot trajectory is parallel with the line of swimming and the foot web is perpendicular to it. But later in the stroke the foot takes an increasingly transverse direction, swinging towards the longitudinal axis of the body. Here we show that, early in the power stroke, propulsion is achieved mostly by hydrodynamic drag on the foot, whereas there is a gradual transition into lift-based propulsion later in the stroke. At the shift to lift mode, the attached vortices of the drag-based phase turn into a starting vortex, shed at the trailing edge, and into spiralling leading-edge vortices along the sides of the foot. Because of their delta shape, webbed feet can generate propulsive forces continuously through two successive modes, from drag at the beginning of the stroke, all the way through the transition to predominantly lift later in the stroke.}},
author = {{Johansson, Christoffer and Norberg, Åke}},
issn = {{0028-0836}},
language = {{eng}},
number = {{6944}},
pages = {{65--68}},
publisher = {{Nature Publishing Group}},
series = {{Nature}},
title = {{Delta-wing function of webbed feet gives hydrodynamic lift for swimming propulsion in birds}},
url = {{http://dx.doi.org/10.1038/nature01695}},
doi = {{10.1038/nature01695}},
volume = {{423}},
year = {{2003}},
}