The hydrodynamic secret of dolphin by drieant.03

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									              The Hydrodynamic Secret
                   of the Dolphin




                                                             G. I. Svyator 1969

Scientists Discover Secret of Dolphin Speed – Ocean Research, 2004
            Power = Drag x Velocity
Velocity = 33 ft/sec (10 m/s*; Re = UL/ν = 1.8x107)
Drag = CD ½ ρ U2 A
Area = 15 ft2 (6-ft long, 200 lbs, 35 lbs of muscle)
CD = f (Re)

       hp/lb of muscle = 0.074 (turbulent – 0.25 if U=15m/s)
       hp/lb of muscle = 0.009 (laminar)
       hp/lb of muscle = 0.01 (men, dogs – prolonged activity*)
Human ingenuity may make various inventions, but will never
devise any inventions more beautiful, nor more simple, nor
more to the purpose than Nature does; because in her inventions
nothing is wanting and nothing is superfluous..
(Leonardo da Vinci 15th Century)
 Drag Reduction Strategies : Streamlined shape
 Cayley (circa 1809)
“We should be
deriving our boat
from a better architect
than man, and should
probably have the
real solid of least
resistance”


Shape of dolphin
  compared
   to air foil
                                         Trout




Relative sizes of wire and streamlined airfoil
   for the same drag (speed = 210- mph)
Large Drag




             Small Drag
1903 – Wright Brothers




                         1950’s – high speed fighter
  Flow Visualization

Resolution of the nature
of the dolphin boundary
layer were tried to be
resolved by a variety of
flow visualization
experiments using:
  particles,
  air bubbles,
  dyes,
  spray,
  temperature gradients,
  and bioluminescence
Flow-Stimulated Bioluminescence




     Bioluminescent Bay in Puerto Rico
          Pyrodinium bahamense
LAMINAR

          TURBULENT
        Forced transition
                      Turbulent


    Laminar
                      Natural transition


Shear stress of 7-1 ellipsoid
            Power = Drag x Velocity
Velocity = 33 ft/sec (10 m/s*; Re = UL/ν = 1.8x107)
Drag = CD ½ ρ U2 A
Area = 15 ft2 (6-ft long, 200 lbs, 35 lbs of muscle)
CD = f (Re)

       hp/lb of muscle = 0.074 (turbulent – 0.25 if U=15m/s)
       hp/lb of muscle = 0.009 (laminar)
       hp/lb of muscle = 0.01 (men, dogs – prolonged activity*)
School of Delphinus delphis:
 maximum speed = 6.7 m/s
        (n ~ 1000)
Capture and Release:
 Tursiops truncatus
max speed = 5.7m/s
      (n ~ 25)
     DOLPHIN SWIMMING SPEED
Highest swimming speed at Sea World for Tursiops truncatus
                  8.2 m/s for 2 seconds
Frequency x Wake Diameter
                            = constant
         Velocity
.1
     25




                 0
                20
                40
                60
                80
               100
               120
               140
               160
               180
               200
     -
.1 . 2 2
  51 5




                             49
     -. 2
.1 5
  76 0
     -


                                             103
.2 . 2 7
  01 5
     -
                                                         151


.2 . 3 0
  26 0
     -
                                                                177




.2 . 3 2
                                                                      Predictions




  51 5
     -
                                                               167




.2 . 3 5
  76 0
     -
                                                   130




.3 . 3 7
  01 5
     -
                                        86




.3 . 4 0
  26 0
                             48




     -
.3 . 4 2
  51 5
                                                                          Figure 5




     -
                        31




.3 . 4 5 0
  76
                   12




     -
.4 . 4 7
  01 5
               8




     -
.4 . 5 0
  26 0
               5




     -
.4 . 5 2
  51 5
               2
                                                                                     Histogram of Cetacean Strouhal Numbers




     -. 5
.4 5 0
               2




  76
     -
                              St # = fD/U




.5 . 5 7
  00 5
               2




     -. 6
          01
               1
The End – Good bye




..but one more secret -
  40% delay in stall if
flipper has tubercles !!

								
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