Kind: captions
Language: en
I'm here at the Navy's indoor ocean at
cter rock this is the biggest wave pool
in the world and they can make all kinds
of different waves so they can test
scale ships and make them better before
they actually go out on the open
ocean I came in I'd seen some pictures
but I just walked in here and it's just
it's insane cuz they say indoor ocean
but like it's exactly what it is the
water even looks ocean colored you it
doesn't look like a swimming pool this
looks like an Ocean looks like a test
facility it is huge it is 360 ft long in
this Dimension 240 ft long in that
Dimension it's 20 ft deep just about the
size of a football field out there the
Dome above us was the largest
freestanding dome for a while largest
freestanding dome in the world yep
what in this pool they can make waves of
all shapes and sizes using huge paddles
that line two walls of the pool we have
216 individual wav makers we can make
waves from -45° up to 135° which is kind
of coming right back at
it we are now behind the big paddles
that make the waves these 216 paddles
are programmed to move in incredibly
well choreographed ways so that they can
produce
reproducible uh perfect size perfect
frequency waves that go across the
entire pool you can see these air
Bellows that are what's making the the
angular motion that vertical piece is
the force transducer the other Force
transducer is right up on the top there
are lots of wave pools in the world but
what makes this one different is control
you can create waves of a specific
amplitude and frequency and do so
repeatedly should we try our 1 Hertz
yeah do me a favor and dial up one Hertz
amplitude will be 078 at 1 Herz hey go
ahead and send it from zero please as
this is the largest wave we can make at
1 Hertz just based on the motion and and
power requirement for the Wave Maker
there's something a bit like surreal
about watching this cuz it almost looks
like an ocean except you never see waves
this regular out there correct one of
the fundamental characteristics of a
wave is its wavelength the distance from
one Crest to the next the first thing
most people learn about waves is they
transmit energy rather than material
from one place to another in this case
as the wave travels to the right the
water molecules themselves basically
Move Along circular paths and the deeper
the water the smaller this motion all
motion stops at a depth equal to half
the wavelength this is known as the wave
base but even in an ideal water wave the
molecules do drift a bit in the
direction of wave motion and this is
because the molecules travel faster the
higher up they are so they move move
farther at the top of their Loop than
they move backwards at the bottom
creating a spiral path this place is
perfect for observing properties of
different waves I asked Miguel to show
me some waves with different frequencies
but the same amplitude so what I'll have
them do now is I'll have them stop this
wave and this changed the frequency cuz
we're at 6 we'll go to 0. five so it'll
be a 2C
wave here I'm split screening waves with
frequencies of
67.5 and3 3 Herz all with the same
amplitude so two things to notice even
though they all have the same amplitude
the ones with higher frequency look like
they have a greater amplitude because
the slope of the waves is steeper and
second the frequency of a wave affects
its speed high frequency waves travel
slower than low frequency waves in fact
as long as the water is deeper than the
wave base wave speed is inversely
proportional to its
frequency they have have a really cool
demo that takes advantage of the
different speeds of different frequency
waves you can see it starting here they
send out high frequency waves first
followed by lower and lower frequency
waves and because the high frequency
waves travel slower the lower frequency
waves gradually catch up
wow and they've timed it so that all the
waves meet up at exactly the same time
and place in the pool this causes the
wave to break the ocean Engineers can do
this
again and
again in exactly the same way thanks to
their precise control over the
waves this demo also nicely illustrates
the principle of superposition that when
waves meet they add together the height
of the water is equal to the sum of the
heights of the individual waves meeting
at that point you can see how much
bigger the amplitude is those individual
waves weren't that big but when you add
them all together you can make this big
breaking
wave they can also take advantage of the
superp position principle to create
standing waves so what's coming up next
are two regular waves coming at each
other what we call the quilt wave so
we're going to have a wave coming this
way and a wave going this way and it's
going to create standing waves so
there's two regular waves coming out and
if you look at the waves it looks like a
big quilt pattern out there at some
places in the pool the waves always
cancel out to zero amplitude and at
other places the waves add up for
maximum
amplitude they can even send waves from
all directions so they form circular
wave fronts and then all the wave energy
is channeled into one spot they call the
bullseye and so now we're going to run
the bullseye wave which is essentially
the same thing but instead of having a
line of waves we're having it all coales
at one individual point so you can start
seeing the waves are coming from the
long bank here you can see the making a
spherical wave and then you have another
spherical wave coming from the short
bank and this is breaking due to the
coalescent waves and the wave height
being more than 17th of the wave
length we tried throwing some toys into
the wave to see what would happen to
them would they get pushed into the
breaking wave even though there's not
much net movement of the water the ducky
drifts with the waves and pretty quickly
is pushed into the
bullseye how's it how's it you doing
he's getting to the danger zone right
now it's starting to funnel him right
into that breaking wave it's there it's
getting up getting
up oh it swamped it that's amazing that
was right where we wanted
it now the real purpose of this facility
is not to play with toys or make perfect
unnatural waves it is to replicate on a
small scale the types of waves Navy
ships will encounter in the oceans of
the world
research Engineers Place ships modeled
after billion dooll vessels in the water
to see how different designs actually
behave in real world conditions right
now this is coming from 45° it's going
to be about a 5 in significant wave
height which if we were to scale it up
for this model would be 20ft waves when
we're doing a free running model like
this we usually run like a racetrack
like a big circle or a figure eight
track so we know the headings that we're
running in so that we can correlate that
to you know the full scale
vessel for the model to provide an
accurate representation of the real
world a lot of things must be taken into
account is the water fresh fresh water
okay not salty nope fresh water so when
you're in salty water you're going to
have a lot more buoyancy so when we're
balasing our models we have to make sure
that they take into account that
buoyancy difference so when we go full
scale you know you're the same
conditions for fluid mechanics I always
expect that you have to keep the
Reynolds number the same as in the real
world World phenomena but actually to
get the right wave Dynamics you have to
use a different scaling which is based
on the frud number so the frud number is
a measure of the ratio of inertial to
gravitational forces it's equal to the
flow velocity divided by the square root
of the acceleration due to gravity times
the characteristic length like the
length of the ship in this case the
model ship's hole is 46 times smaller
than the real thing which means to get
accurate data it should be traveling at
1 over the < TK of 46 time its real
world speed and to make the footage from
the model look the same as that from the
full-size ship you have to slow it down
by a factor of the square < TK of 46 so
roughly 6.8 times slower I'm amazed at
just how well these shots match but of
course that's the idea scale the model
and the waves so the physics are
identical to a real ship out on the open
ocean naturally I add asked if I could
go swimming in the pool but they said
very kindly no way the closest I could
get would be on a little dingy this is
our
boat with a
catch it's pretty smooth uh smooth
sailing out here right now yep no waves
while we're out
here so I'm assuming no one's ever been
out here in waves no that's one of the
no no they don't want us to do I guess
it's a risk thing so this Place seems
like a I don't know like a massive
playground kind of it kind of is for uh
Engineers like us where it's we kind of
Dork out on the science and what we're
doing here it's it's a huge volume like
I I guess I never understood how deep 20
ft was until they emptied it to put in
the new wave makers it's a large volume
just taken up by this water um yeah so
as we come by these are our sensors
right here we have a big array here um
these are ultrasonic sensors and that's
how we measure wave height and period
and direction in the Basin so we want to
make measure that to make sure that what
we test in is what we think we have in
this pool they can create all sorts of
different wave conditions you might
encounter in different parts of the
world most ocean waves are created by
wind and the strongest winds occur in
and around
storms five factors affect the size and
shape of waves created these are the
wind speed the wind duration the
distance over which the wind is acting
which is known as the fetch the width of
the Fetch and the depth of the water as
waves travel out from a storm the higher
frequency waves dissipate their energy
more quickly so the waves that travel a
long way are the fast moving low
frequency waves which are called swell
when those waves end up becoming like
hundreds of miles away like if you have
it in the Pacific eventually you'll get
long period swell from them so you're no
longer near the this the storm but it
created enough energy to make long waves
and that's where you get your open ocean
swell tell me if this is a good analogy
I feel like with sound a lot of the high
frequencies will die off quickly away
from a source but the low frequencies
will travel much further correct so is
it the same thing with the waves it's
like like you're walking away from a
concert and you can hear still hear like
the bass but you can't see any of the
high high fre great analogy yep what's
the deal with rogue waves people like to
think it's a rogue wave where it's just
came out of nowhere and just came up no
it's usually multiple waves that are
meeting up and creating an amplitude
that's much larger than what the
self-standing wave would be so when it
meets it's going to break because you
have this large wave creating this huge
amplitude that it just can't hold it and
it breaks on a calm day when you see
waves crashing at the beach around 10
seconds apart that is swell but because
of its long wavelength swell isn't
really a concern for ships out in the
open ocean you know if you're on a long
period swell your ship's probably just
going to heat a little bit you're more
worried about the Steep waves and the
windy waves that are really moving you
around wind waves are formed in three
steps first as Wind Blows across the
surface of perfectly still water the
turbulent motion of the air creates
regions of slightly higher and slightly
lower pressure and this makes tiny
ripples with wavelengths of around a
centimeter but now the wind can act on
these ripples creating larger pressure
differences between the front and the
top of the wave Crest pulling them up
into bigger waves and the interaction of
the wind with these waves then creates
even larger pressure differences and
even larger waves the waves are mostly
uniform at this point but as they
interact with each other they create a
range of different wavelength waves and
as the wind keeps blowing these waves
begin breaking transferring their
kinetic energy into swirling Eddies that
dissipate their energy as heat once the
energy dissip matches the energy input
from the wind the waves have reached
their maximum size and this is known as
a fully developed
CA so this is going to be an irregular
wave this is irregular irregular wave so
the what you saw earlier with the
regular waves where one frequency one
amplitude this is what we call a Spectra
or multiple frequencies and multiple
amplitudes you can see there's like
higher frequency waves that kind of go
travel slower than the low frequency
waves those low frequency waves will
travel fast and overcome them and that's
what's making them look peaky or kind of
dulling it
out what surprised me is that the
different oceans of the world have
different mixtures of wave frequencies
or different Spectra depending on their
geography and the types of storms that
occur there for example the North Sea
and other small bodies of water have a
peier spectrum and this is due to the
limited fetch of storms that occur there
in the mid Atlantic a broader Spectrum
best describes the developing or
decaying open ocean waves that you'd
find there and in the North Atlantic the
steady wind across an open ocean
produces the broadest spectrum of wind
waves so when testing engineers first
have to figure out where the ship will
be deployed and which Spectra best match
these locations before creating them in
the pool for most people I think an
ocean is an ocean but you're saying that
there's sort of like different
conditions depending on where you are
the Destroyer when I was in command we
did an operation off the coast of South
Korea in the spring very rough seae
keeping conditions but then like when
you're crossing the Pacific a lot of
that is a lot calmer uh so again you
know from there to uh the coast of South
Korea to the Arabian Gulf all those very
different conditions were there any
conditions that were particularly rough
for you so uh my bed was actually in the
middle of a room and the Seas were so
bad and this is either south or east
China Sea the Seas were so bad that one
night I woke up in the middle of the
night and my whole mattress with me on
it was sliding off of my bed frame um
and that's a pretty significantly sized
mattress so you can imagine the Seas we
were in that
night much bigger than this would
terrify me I know it probably looks
benign
but like much bigger than this I think
that model will take a lot of
water why do you care about how much
water goes on the deck so on the back of
this ddg is a helicopter landing pad
they don't want any water on the deck
when a helicopter's about to land that's
a big problem you know that's one of the
tests that we do here is we'll put
cameras to look at the deck and
understand how much water wash is
on since I knew they wouldn't want to
risk their fancy model in rough
conditions we brought along a little
remote controlled boat to test
yeah I wouldn't be happy on that
boat a lot of people would be getting
seasick
W wa no is it gone it's gone no it's
right there it came up it's upside
down it was totally gone I it was in the
air and then it went
under now not all the models tested here
can be remote controlled so on the
carriage is where we're going to do
captive mod model test where you could
tether put Power and instrumentation
onto a model that can't hold it itself
so usually the model will go in this
Moon Bay right here the models are
hooked up here and then the whole Lab
speeds over the waves Towing the model
underneath people have been making ships
for thousands of years mhm is there
actually any Innovation today most
definitely so sometimes you know people
say that's the way we've always done it
and then when you look into it there's
some validity to some hairbrain ideas
and when we test them that's why you
know you cut your cost of doing a model
test versus building the full thing and
saying oh that didn't work every ship
that's in the Navy's fleet has gone
through here has gone through either our
purview or has been tested with
perfectly with us but Mo all of the Navy
owned ships have been tested in this
facility and there is a ship out there
with a tumble Home Design where if you
look at this ship behind you it flares
out so this flare is usually what helps
protect you from when you start rolling
it gives you a reaction force or gives
you a helps push you back a tumble home
is shape you know the opposite direction
and if you have a ship shaped in that
direction it doesn't have as much of a
restoring Force when you roll but what
is the idea with making a ship like that
there's a lot of different reasons why
you want to change a whole design some
of it is the above water signatures it's
all about the shape and radar sections
and you know that there's a lot that
goes into that you always want to be
stealthier you always want to be faster
you always want to have more power power
and that's always what you know the
Innovations
come so most of the sailors aren't aware
of the work that's going on in the
background to support what they do um
when I was in The Fleets and I've been
in the Navy 27 years I never had any
idea certainly not the magnitude of what
they do I'm not exaggerating when I say
it's impacted every ship and submarine
in the fleet
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