Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental...
-
Upload
caren-chandler -
Category
Documents
-
view
214 -
download
1
Transcript of Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental...
![Page 1: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/1.jpg)
Biomechanics of propulsion and drag in front crawl swimming
Huub ToussaintInstitute for Fundamental and
Clinical Human Movement Sciences
Vrije Universiteit, Amsterdam, Holland
www.ifkb.nl/B4/[email protected]
![Page 2: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/2.jpg)
![Page 3: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/3.jpg)
Buoyancy
Weight
Drag Propulsion
![Page 4: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/4.jpg)
How is propulsion generated?
Pushing water backwards
![Page 5: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/5.jpg)
Viewpoints:
![Page 6: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/6.jpg)
Front crawl kinematics
Pushing water backwards?
![Page 7: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/7.jpg)
Hand functions as hydrofoil
![Page 8: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/8.jpg)
Hydrofoil subjected to flow
![Page 9: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/9.jpg)
Hand has hydrofoil properties
![Page 10: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/10.jpg)
Lift and drag force
![Page 11: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/11.jpg)
Adapt to direct Fp forward
![Page 12: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/12.jpg)
Quasi-steady analysis
![Page 13: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/13.jpg)
Quasi-steady analysis:Combining flow channel data with hand velocity data
![Page 14: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/14.jpg)
MAD-system
![Page 15: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/15.jpg)
Propulsion: ResultsQuasi- steady analysis vs MAD-system
![Page 16: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/16.jpg)
Does the quasi-steady assumption fail?
How to proceed?A brief digression
The aerodynamics of insect flight
![Page 17: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/17.jpg)
‘The bumblebee that cannot fly’
Quasi-steady analysis cannot account for
required lift forces
Hence, there must be unsteady,
lift-enhancing mechanisms
![Page 18: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/18.jpg)
Delayed Stall
Unsteady lift-enhancing mechanism
Add rotation…. and visualize flow
![Page 19: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/19.jpg)
Hovering robomoth
![Page 20: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/20.jpg)
3D leading-edge vortex
![Page 21: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/21.jpg)
Delayed stall: the 3D version Leading-edge vortex stabilized by axial flow Can account for ~ 50% of required lift force Key features:
– Stalling: high angle of attack (~ 45º)– Axial flow: wing rotation leads to an axial
velocity / pressure gradient– Rotational acceleration (?)
![Page 22: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/22.jpg)
So what’s the connection?
![Page 23: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/23.jpg)
...back to front crawl swimming
Short strokes & rotations: unsteady effects
probably play an important role
Explore by flow visualization
Our first attempt:– Attach tufts to lower arm and hand to record
instantaneous flow directions
![Page 24: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/24.jpg)
![Page 25: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/25.jpg)
Outsweep
![Page 26: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/26.jpg)
Accelerated flow
![Page 27: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/27.jpg)
The pumping effect arm rotation pressure gradient axial flow
![Page 28: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/28.jpg)
Toussaint et al, 2002
![Page 29: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/29.jpg)
![Page 30: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/30.jpg)
Buoyancy
Weight
Drag Propulsion
![Page 31: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/31.jpg)
Drag:
friction pressure drag wave drag
![Page 32: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/32.jpg)
shipv
![Page 33: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/33.jpg)
Divergent waves
Transverse waves
ship
![Page 34: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/34.jpg)
Effect of speed on wave length
Wave drag 70% of total drag
(of ship)
![Page 35: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/35.jpg)
Length of surface wave
2v2
g
Hull speed for given length (L) of ship:
v
Lg
2
![Page 36: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/36.jpg)
Height of swimmer 2 m:
L 2
v 2 9.812 3.14
1.767 m / s
Hull speed for a swimmer
“Pieter” swims > 2 m/s…..
![Page 37: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/37.jpg)
E T B R C S M J Mean0
10
20
30
40
% o
f to
tal d
rag
subjects
MAD-method
Wave drag as % of total drag
12%
![Page 38: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/38.jpg)
Summary
humans swim faster than ‘hull’ speed wave drag matters at competitive swimming
speeds but is with 12% far less than that for ships where it is 70% of total drag
![Page 39: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/39.jpg)
Interaction length of ship (L) with wave length (l)
![Page 40: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/40.jpg)
hull speed
reinforcement
cancellation
reinforcement
![Page 41: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/41.jpg)
hull speed
![Page 42: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/42.jpg)
![Page 43: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/43.jpg)
Could non-stationary effects reduce wave drag?
![Page 44: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/44.jpg)
Takamoto M., Ohmichi H. & Miyashita M. (1985)
![Page 45: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/45.jpg)
‘Technique’ reducing bow wave formation?
Glide phase: arm functions as “bulbous bow” reducing height of the bow wave
Non-stationarity of rostral pressure point prohibits full build-up of the bow wave
ship
![Page 46: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/46.jpg)
With whole stroke swimming speed increases about 5% without a concomitant increase in stern-wave height.
The leg action might disrupt the pressure pattern at the stern prohibiting a full build up of the stern wave
![Page 47: Biomechanics of propulsion and drag in front crawl swimming Huub Toussaint Institute for Fundamental and Clinical Human Movement Sciences Vrije Universiteit,](https://reader038.fdocuments.us/reader038/viewer/2022110206/56649ce25503460f949ad7c5/html5/thumbnails/47.jpg)
THANK YOU FOR YOUR
ATTENTION