INSTANTANEOUS VOLUMETRIC WAKE ANALYSIS OF LOCOMOTION … · Total volume imaged was 14*14*10 cm....

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11

22

Bro

oke

E.

Fla

mm

an

g,

Ge

org

e V

. L

au

de

r,

Da

nie

l R

. T

roo

lin,Tyso

n S

tra

nd

12

Museum

of C

om

para

tive Z

oolo

gy,

Harv

ard

Univ

ers

ity,

Cam

bridge, M

A, 02138, U

SA

. F

luid

Mechanic

s D

ivis

ion, T

SI In

corp

ora

ted, S

t. P

aul, M

N, 55126, U

SA

INS

TA

NTA

NE

OU

S V

OL

UM

ET

RIC

WA

KE

AN

ALY

SIS

OF

LO

CO

MO

TIO

N IN

TE

LE

OS

T F

ISH

ES

AB

ST

RA

CT:

Pre

vio

us s

tudie

s o

f th

e w

ake h

ydro

dynam

ics o

f fishes h

ave

been r

estr

icte

d to tw

o-d

imensio

nal dig

ital part

icle

im

age v

elo

cim

etr

y (

DP

IV)

slic

es b

y a

vaila

ble

technolo

gy.

B

y c

om

paring m

ultip

le s

lices, pre

vio

us

researc

hers

hypoth

esiz

ed the thre

e-d

imensio

nal str

uctu

re o

f th

e v

ort

ex w

akes

pro

duced b

y s

wim

min

g fis

hes. In tele

ost fishes, such a

s the b

lueg

ill s

unfish,

the h

om

ocerc

al ta

il pro

duces a

sin

gle

jet w

ith e

ach late

ral pass. U

sin

g

conventional tw

o-d

imensio

nal D

PIV

, vort

icity s

hed b

y the h

om

ocerc

al ta

il w

as

vis

ualiz

ed a

s tw

o c

ounte

r-ro

tating v

ort

ice

s w

hic

h w

ere

hypoth

esiz

ed to b

e

part

of a thre

e-d

imensio

nal ro

tating r

ing

thro

ugh w

hic

h a

jet of fluid

passed.

Now

, usin

g a

volu

metr

ic D

PIV

syste

m, w

e h

ave c

onfirm

ed that th

e thre

e-

dim

ensio

nal str

uctu

re o

f th

e v

ort

ex r

ing p

roduce

d b

y the h

om

ocerc

al ta

il fin is

indeed a

s p

redic

ted. In a

dditio

n, m

ultip

le late

ral passes o

f th

e tail

pro

duced a

lin

ked c

hain

of vort

ex r

ings. U

sin

g this

volu

metr

ic D

PIV

syste

m w

e w

ere

als

o

able

to insta

nta

neously

captu

re the thre

e-d

imensio

nal w

ake inte

ractio

ns o

f th

e d

ors

al and a

nal fins w

ith the c

audal fin in b

oth

liv

e fis

hes a

nd r

obotic

analo

gs.

HY

PO

TH

ES

IS 1

: E

ach

la

tera

l p

ass o

f th

e h

om

oce

rca

l ta

il p

rod

uce

s a

sin

gle

je

t o

f flu

id,

wh

ich

pa

sse

s t

hro

ug

h a

vo

rte

x

rin

g.

Mu

ltip

le la

tera

l p

asse

s

pe

rfo

rme

d d

urin

g s

wim

min

gp

rod

uce

a s

erie

s o

f lin

ke

d v

ort

ex

rin

gs.

(Fig

ure

fro

m L

au

de

r a

nd

D

rucke

r, 2

00

2)

HY

PO

TH

ES

IS 2

: V

ort

icity

pro

du

ce

d b

y t

he

do

rsa

l a

nd

a

na

l fin

s o

f a

sw

imm

ing

fis

h

inte

racts

with

th

at

pro

du

ce

d b

y

the

ca

ud

alf

in.

(Fig

ure

fro

m

Tyte

ll, 2

00

6)

Fig

. 1

Fig

. 2

Fig

. 3

Fig

. 1

. E

xp

erim

en

tal

arr

an

ge

me

nt

of

the

flo

w t

an

k,

lase

rs,

an

d v

olu

me

tric

im

ag

ing

syste

m f

or

ca

ptu

rin

g t

he

in

sta

nta

ne

ou

s v

olu

me

tric

wa

ke

b

eh

ind

fre

ely

sw

imm

ing

fis

he

s

an

d r

ob

otic t

ail

mo

de

ls. To

tal

vo

lum

e im

ag

ed

wa

s 1

4*1

4*1

0

cm

.

Fig

. 2

. V

olu

me

tric

3-c

om

po

ne

nt

ve

locim

etr

y (

V3

V)

vo

lum

etr

ic

flo

w im

ag

ing

trip

od

ca

me

ra

pro

be

ca

ptu

red

im

ag

e p

airs a

t 7

.25

Hz w

ith

a t

ime

of

35

00

us

be

twe

en

ea

ch

im

ag

e p

air a

t 1

2

bit r

eso

lutio

n.

Fig

. 3

. S

ch

em

atic

rep

rese

nta

tio

n o

f 3

D

pa

rtic

le id

en

tifica

tio

n.

Pa

rtic

le im

ag

es f

rom

th

e

left

ima

ge

(L

) a

re

rep

rese

nte

d b

y w

hite

,p

art

icle

im

ag

es f

rom

th

e

rig

ht

ima

ge

(R

) a

re

rep

rese

nte

d b

y r

ed

, a

nd

p

art

icle

im

ag

es f

rom

th

e

top

im

ag

e (

T)

are

re

pre

se

nte

d b

y b

lue

.T

he

ce

ntr

oid

of

the

trip

let

rep

rese

nts

th

e x

an

d y

loca

tio

n,

the

an

d t

he

siz

e

giv

es t

he

z lo

ca

tio

n.

(Fig

ure

fro

m T

roo

lin a

nd

L

on

gm

ire

, 2

00

9).

RE

FE

RE

NC

ES

:

La

ud

er,

G.V

. a

nd

E.G

. D

rucke

r. (

20

02

) F

orc

es,

fish

es,

an

d f

luid

s:

Hyd

rod

yn

am

ic m

ech

an

ism

s o

f a

qu

atic lo

co

mo

tio

n.

Ne

ws P

hysio

l S

oc 1

7:2

35

-2

40

Tro

olin

D.R

. a

nd

E.K

. L

on

gm

ire

. (2

00

9)

Vo

lum

etr

ic v

elo

city m

ea

su

rem

en

ts o

f vo

rte

x r

ing

s

fro

m in

clin

ed

exits.

Exp

Flu

ids

DO

I 1

0.1

00

7/s

00

34

8-0

09

-07

45

-z

Tyte

ll, E

.D.

(20

06

) M

ed

ian

fin

fu

nctio

n in

blu

eg

ill

su

nfish

Le

po

mis

ma

cro

ch

iru

s:

str

ea

mw

ise

vo

rte

x

str

uctu

re d

urin

g s

tea

dy s

wim

min

g.

J E

xp

Bio

l 2

09

:15

16

-15

34

Fig

. 4

. (A

) R

ob

otic s

imp

lifie

d h

om

oce

rca

l ta

il m

od

el in

la

se

r vo

lum

e a

nd

(B

) vo

lum

etr

ic

reco

nstr

uctio

n o

f w

ake

pro

du

ce

d.

No

te h

ow

do

wn

str

ea

m e

dg

e c

on

str

icts

je

t (w

hite

arr

ow

s).

ME

TH

OD

S:

Fig

. 8

. (A

, to

p)

Vo

lum

etr

icre

co

nstr

uctio

n o

f w

ake

of

a

blu

eg

ill s

un

fish

sw

imm

ing

fa

r b

ack e

no

ug

h in

vo

lum

e t

o s

ee

w

ake

pro

du

ce

d b

y t

he

do

rsa

l fin

(o

utlin

ed

in

re

d).

(B

, b

ott

om

) P

lan

ar

slic

e (

XY

) th

rou

gh

vo

rte

x c

au

se

d b

y d

ors

al fin

, co

lore

d b

y z

vo

rtic

ity.

Ta

ng

en

tve

cto

rs a

re d

isp

laye

d a

nd

in

dic

ate

dire

ctio

n a

nd

ve

locity

of

flo

w,

with

me

an

str

ea

m f

low

ve

locity s

ub

tra

cte

d.

AB

Fig

. 5

. (A

) L

ive

blu

eg

ill s

un

fish

sw

imm

ing

in

la

se

r vo

lum

e a

nd

(B

) vo

lum

etr

ic

reco

nstr

uctio

n o

f w

ake

pro

du

ce

d (

at

40

% t

ran

slu

ce

ncy).

* =

tra

ilin

g e

dg

e v

ort

ice

s

se

pa

ratin

g f

rom

ta

il fin

.

AB

AB

Fig

. 6

. (A

) L

ive

cic

hlid

sw

imm

ing

in

la

se

r vo

lum

e a

nd

(B

) vo

lum

etr

ic r

eco

nstr

uctio

n o

f w

ake

pro

du

ce

d.

AB

Fig

. 7

. (A

) R

ob

otic b

lue

gill

ho

mo

ce

rca

l ta

il m

od

el in

la

se

r vo

lum

e a

nd

(B

) vo

lum

etr

ic

reco

nstr

uctio

n o

f w

ake

pro

du

ce

d b

y t

he

do

rsa

l (r

ed

), a

na

l (b

lue

) a

nd

ca

ud

al (g

ree

n)

fin

s.

A B

-5.0

5.0

0-1

Z V

ort

icity (

s)

* *

CO

NC

LU

SIO

NS

:

The a

bili

ty to c

aptu

re a

n

insta

nta

neous s

napshot of th

e

com

ple

te w

ake s

tructu

re

pro

duced b

y a

sw

imm

ing fis

h

rem

oves the p

ote

ntial err

or

involv

ed w

ith p

revio

us

technolo

gie

s, w

here

re

searc

hers

had to inte

gra

te

multip

le d

ata

sets

to p

roduce

a 3

D s

tructu

re. U

sin

g this

new

technolo

gy,

we h

ave

confirm

ed that hom

ocerc

al

tails

pro

duce a

series o

f lin

ked

ring v

ort

ices d

uring s

teady

sw

imm

ing. W

e h

ave a

lso

been a

ble

to identify

dors

al

and a

nal fin w

ake s

tructu

res

and a

re b

egin

nin

g to b

uild

a

better

unders

tandin

g o

f how

th

ey inte

ract w

ith the w

ake

pro

duced b

y the c

audal fin.

An

ag

lyp

h o

f F

ig.

6B

, vie

w w

ith

3D

gla

sse

s.

DO

RS

AL

FIN

JE

T

FIS

H B

OD

Y

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