Thank you for just the right thing and
I'm pretty new yes I joined.

Before that I was there exists
an amplifier so most of the work which I'd

be showing is done a Texas A and M.
And in that transition phase and

just on the sly it's a shock but I learned
that this is more than the ocean is about

the sort of things were inside taken out
of it's I'm not going to talk about shock

that mostly talk about the dynamics
of buoyancy driven and

in the middle of the discussion to show
you how those two are interrelated.

So.

I'm here on the behalf of
all the students who have

done the work I'm just taking
the goatee coming and.

So on the top of the most of
the world which I'll show here

by the nation Sharon and
they have just finished there.

And I have one who just following
this vote here at Georgia Tech.

And there's not a for funding funds
which is supported by the N.S.F. and

the Air Force and is to get it aboard as
well as there's a lot of efforts in this

area from National Security Administration
they want to know about this instability

because it's driving some
things in the environment.

So that there are thirty basic What do
you mean by a buoyancy driven flows so

buoyancy driven flows if you've not heard
you must have heard about the really.

If you don't know what I'm going
to talk about if you drink

coffee in the morning and

I like to take my coffee with milk always
because i can they get a black coffee or

the milk and I can see the structure
forming both structures are basically

driven by relating to instability what
that instead it is basically you have to

flow it's you can have a heavy fluid
fluid in a gravitational field or

the explanation which is given from every
to light and you become unstable they'll

try to make any kind of perturbation and
use the most that's much easier

if i have anybody to be asian this boat
a bit of a dry and at the end of day the.

To makes two different foods which are two
different densities our interest is

to figure out what drives this force what
is the driving mechanism which drives this

mixing and
is there a way to point to fight there.

And for quantification we are looking
at films which is called density

Congress I'll talk a lot about that
this is at one number it's just density

does between these two
flu it's not enough.

And the driving mechanism which happens
is if you if your idea about a clinic or

a city question there's
a by opening the talk and.

So in this case you are below comes from
density difference between these two

fluids and then becomes from your pressure
gradient because of the gravitational.

And the cross product defines
what's going to be your and

want to hold the city deposited
this is what a city deposit it was.

But if you want to take a step back and
just look at inflated mechanics

What are different ways the study problem
so there are three different problems you

look at what is a very simple problem of
mixing of bodies and that's a scalar and

the passive scalar does not belong to
a class it's a model you can develop and

things will be basically normally that
in species there's no density changes or

you're looking at how
basically moves in the flow.

But then there's a second clause which
we're going to look at today is mixing of

fluids the child different densities and
when the mix happens

between these two fluids the dynamics
of the mixing is driven by what they

will also to feel also so the dynamics
will drive the mixing of the flow so

that's called us to do your
second kind of mixing and

it's driven in the thermal convection
you have already had like a village in

flows you can have this in the mix
convection reason of washing flows so

there's a very dynamic system which is
driving through and the third thing which

is in the aerospace industry is think
about is OK I want to burn something.

I want to run things at the heart of
the you're looking at things that

if you mix two different flu it's not
the mixing between those who feel it's

the it's a third species and you want to
look at what that species rate will be so

that's your combustion supernova and
all those things into it is

the question I'll do mostly focusing
on more how the makes in the fluids and

different density that's affected
by dynamics of the flow and

vice versa.

So so I'll come but.

Let me quote something so a James Bond
movie everybody have heard he likes

to take his ring shaken not stirred so
that he did there's a two different ways

of mixing you're thinking about if you
start something it's just creating a large

motion of the flow for you you don't know
what the molecule level of mixing so

in trainmen has to a different than
what you define mixing what I'm showing

there right now is just in trainmen
it's just a fluid into fluid B.

and you're just defining
what being trained part is

if you want to do you know what the level
of making is you have to do molecule or

mixing resume there to see what
exactly is fluid if would be in point

five all infractions are in their
different ways we're going to be.

Most of the people so far in this field
they were always interested in and

iteration and which is just in Feynman and
they said OK I just get obeying trainmen

If the density contrasts between
these two fluids small so

I am the both of us approximation feel
as them everything is mix in that So

that's that's whole people
have looked at this area.

So.

I.
Said You start with something which is

looks like some perturbation and
it grows into looks like something like

in train reason where it goes
through three different states so

that's from the experiment
the image from our experiment so

the three stages that she
have a very early phase

you have initial bit of exponential
growth of very small put a big.

Having the flow feel that perturbation
will grow and as the amplitude starts

to grow and amplitude is half of the
variable and they start to merge so the so

let's think about you have different
things which is moving up and down so

the movement of each is affected by what
the next neighbor element is moving so

that's basically going to be called a
bubble measure and when I say a bubble and

Spike I'm going to differentiate
between fluid which is falling down

the food which is falling down
is going to be called spike

food which is rising the light food which
I did that's going to be called Bubble.

So the light fluid which is moving up and
you can just think aboard buoyancy drag

forces which is acting on that so
in an independent ration of these two it

will depend upon what
the neighboring elements is doing.

So people have looked at different methods
of trying to do for gunshot model which is

a recent model that looks at after
a certain point in there isn't thought

a cream the bubble velocity becomes
constant so the bubble is going into

constant velocity That's the prediction
they have and if you think about.

Things like if it was a heavy fluid and

density contrast is almost like one that's
like a free falling free fall out for

a given object there should go as a splash
which is what you would gravitation and

fluid which happens in the flow field so
that's what the velocity would look at.

Here in this region is what we call
a mode coupling so they're different

Mort's which are generated and at the end
of the after the more couples there

will be a dominant mode which gets created
so which is the most dominant mode and

that dominant more they'll drive
you intertainment region so

there are two different things we want
to understand in this know what drives

this coupling of the more what's happening
which is the most dominant mode and

and the only thing is that of the that we
can think about it can control the mixing

will be which means is there are they for
me to perturb the system in such.

The only that the memory of initial kind
of condition still persisted the late

thing that's a couple of ideas
that we're trying to do and

why that is important because.

If this flow reserve then the field
condition memory at late again you can use

that as a tracer you know what level
of mixing you have at certain point.

So I'll come back to that
that's that's the whole

thing which we have
started looking into this.

Is the the the turbulent flow
field which gets created in these

kind of environment is much different
than what you have in the Komodo.

So a little flow is not.

That you cannot as a single fluid dynamics
of the looking at single fluid mixing in

there a little of those so you can
start plotting as we go to the gates

of the tickets on that minus five Third
you can see for very simple cases but

there it is that show that it's not.

Just what is Why do we care so so
from the initial eighty of the having

spent looking at ocean makes clear
what's going on in that environment but

my interest basically comes from these
three projects so I'm interested

understanding so on the sold out that
direction sight of the surface of the sun

you have this solar granules which I get
from so what drives these structures and

it's not really here but the know
the nature of people became very recently

last year which looked at what what is the
reason of these formation these are just

the ONLY from Tommy convection is there
some other driving mechanism which is

going on Fernando they have postulated
that it might be coming from late in

the flows that drives these bubbles Spike
structure which is similar there and

it was there in the in the still World
which was done by the fuller convection

they thought these new structure
which is very similar to the flows so

one of the interests which we
are trying to do here is to.

Understand when you have a very
large density country is it possible

to understand what drives this makes
in and I'm looking at very large and

city countries most of the work is
done for low density country so far.

The other area which I am involved with is
looking at a national confinement fusion

that's an area in which they're trying to
create an environment to achieve fusion

and this is done at Lawrence Livermore
National and the idea here is you take

a large amount of energy from
the laser deposit on a target which is

very small and these targets
are made of isotopes of hydrogen and

they're going to basically bombarded a lot
of energy that they want to fuse but

the problem is when they
make this Stargate and

to get the energy from the laser who the
target they have in my data which is but

really I'm rich absolves I made a blitz
and when the ablation happened the shock

front goes inside but when the shock
is going in it's taking some of the but

helium material in the you know to
try to make the capsule that you have

from knowing that they're in
compressing simply you know to hydrogen

fuel you're compressing hydrogen fuel as
by the amount of the things which you have

which is the higher density seen are going
to get the same Come pressure and

that means you're not going to
get the compression required for

reaching high pressure high
temperature for fusion and

that was one of the reason if you they saw
in the C N N Last year there was a failure

of the near what they were thinking
aboard they're going to achieve fusion of

good which is three times more energy than
what they're putting in They've almost

like point eight zero point nine And
I think that's led to a boat five billion

dollars of their spend in the last ten
years and I think their fundamental issues

the board the toppling of these things and
the idea they had at that point in early

two thousand is if I'm driving that such
a large force and you have such a short.

There's mixing will not take place in that

timeframe this is a very short time
frame for it makes a brilliant.

With other targets so if my energy is
pretty large I don't have a problem with

this mixing and that's what the reason if
you look at the progression of the NIF

it came from that which was fifty lasers
and all the A hundred ninety two but

first this is all it is moved towards
If I start putting in the Laser I think I

should be able to teach
compression which is required.

From the mathematics time point this
comes back to why it's not a call go for

you so if you look at that and
also average equation.

It's very similar but in this is when you
have variable density flows you get a.

Which depends upon the coupling
of your density and

you will also be fluctuations
The These times are not both so

for for the closer you need to
have definitions of density of and

also be crossed correlation and
we need to know this so we are looking at

methods they can try to get the values
of those times from our experiments and

this is much different than what people
have been in that she had given and let me

point out one more thing and she had
them in flow which is very different so

most of the fluid are problems which
was done with a single fluid but

the Shia in that ship production your kind
of energy production or some mean velocity

gradients in this is that's not true then
there's the dominant forces direction

of the acceleration so it's a gravity for
the same being the Shah given for

the of a shot which has the preferential
direction so it's a different flow feel so

so expecting it the dynamics which
is right when you mean production is

different by that later time to dissipate
and everything to behave the same as

one of the flow what was a very
simple approximation we can do

no we are doing this calculation
of looking at these things and

we know that this is not true it might
look like my math third but we don't know

whether it's going to happen in every
environment which has these kind of.

Probably the sciences who
are pushing why this is different.

So it is a local problem
it's still a local.

It can if you go very far it can but in
most other dynamics of the system which we

are driving we don't have
a fire feel environment.

When they need to open a system after
a couple of decades you will see in

the sheer flows you start looking
at looks like a corner of it does.

Yet.

Have a.

Perfect.

Near the surface.

So to look at the closer people have
done this work over the last sixty five

years and they try to look at different
things is it possible to have

been clean man which is done in the height
so height is what we're going to call and

they say OK I know that for the free fall
it should go as square as it has like

a square let's put a come there and
maybe I'll fall is maybe depend upon

density can dress or
may not be dependent on city countries so

they looked at different experiment from
fifty years to our late two thousand and

at that point they were more interested
in just looking at what they meant but

later from two thousand people started
looking at OK in shame it is not Don't

leave a we can define this problem
we need to know what they're told

in the statistics what the opening the
brain is doing what the Flextronics that's

what other group is mostly are looking
at and we're trying to do with the P.

I mean at the measurements to get our
local measurement of these things and

then build up on the whole structure.

So here's some of the previous work
which was done on the cob this is a very

classical vocal lead and this is
still one of my favorite both because

what they did is they put
a system of two fluid.

Put it on the rail system and they can
move it to different gravitational forces

so they were changing not just the fluid
but their change in the gravitational

forces which you have so exploration
due to gravity it was in the system so

it was not an image it was just what
you get on the twenty meter but

they went below a hundred G.
experiment they did in this but

the diagnostics was not very clear so they
can get some makes there but they don't

know what exactly is makes at that point
they only know the extent of that makes.

That was the work done at U.K.
Cambridge and I.

Thought this was a very clever expand
because what they did was they have stored

quarters and and
basically a pure water the put a plea and

they retracted the plate so basically
heavy a light it's going to make and

they can do in this environment
very nice flows lation so

they did the imaging at this point but

the system was limited to very low density
contrast that was the one big problem.

Similar to that more other group did was
a Texas individual before me Malcolm And

he built a water tunnel and he transformed
this problem from a box type with

something which is a convective system so

they said OK let's try to float two
different fluids at the same velocity but

different densities and then we're
going to look at how they're mixing So

this is basically a cold water this is
hot water and they start to makes and

these are the concentration we can look
at backlit system what the mixers.

But he did a one thing which was
very interesting he did the salt and

you'll want to experiment and added
the acid and base in these two and look at

the final killing by the concentration of
bad diet changing and acid and basic and

controlled that gave him a direct
measurement of the mixing it is.

That's the replica of this and these
the same density matched if they did or

water and cold water but
that this was a salt and water.

But but
all this work if you look at it this is.

Limited to a very dense low density
contrast they're looking at to add one

number for both point zero zero
zero one that's a very low density.

This is the whole don't add
Wisconsin what they did was they

said OK there's a different problems
which we can look at here is what's

going on with the initial condition as
the S. and we go higher density country.

So they did this system in
a magnetic The logical fluid so

they added this to be am on a fluid
over the water they can shape the M.R.

fluid the demand they feel they have so
they can put a different experiment

they set it up and then they do is this
a magnetic field so they can remove it

from a bit and then the fluid mixes so
this is the case you start with something

that you have any nice sinusoidal And
then if it just a pure air you don't think

any kind of mushroom structure you just
see a penetration and that is going on but

the problem with this system was
it's very hard to control it and

at the same time when you do I'm
off the optical diagnostics with

that does not allow you to happen it's
not a laser beam started going into X.

ray which has a very low resolution.

This is a what I call is a medieval device
for torturing you can remove that but

this is basically a sledge system they
have this is a work done at Jacob's group

in Arizona and I think what they're trying
to do is they can change the explanation

due to gravity they can hear on that
liquid which have mass densities so

no you don't have problem with the density
contrast that the optical diagnostics and

they can use like they're not limited to
just using water they're using different

fluids so they can go to high density
countries they can do experiments for

admissable as well as immiscible
fluids and they're done to

live similar to the image group they
did with forced and then UN forces what

they call is a normal perturbation you can
have on a fluid and let it go for certain.

This sure that for both force and.

Condition the growth rate is basically
the same and their logic was that this

experiment I can say now that memory
of financial condition is not present

in really telephotos So that's that's
what I want to mean there's a game on and

I think this paper is coming
on in twenty fourteen.

So if you want to summarize what's
what's going on in this area and

you would like to have based upon all the
world and application site you want to be

in the far right corner of the on
the clean pad I'm going to.

This is the add one number has density
Conversely you have the one row two

there's just one minus through two so if
you have very large density countries it

means one and if it's a low
density contracted for that's.

So what you have here.

Is most of the world which is done it's
done till point one where they have very

good data in looking at but also D.C.
and the patent meters.

So we wanted to come and do work in this
area and look at the start of sticks so

that's what my main interest was.

So to do that we have developed this
system there it's in the same technique

as flowing water but rather than flowing
water we have gone to a wind tunnel kind

of system where we are doing flowing
gases so it's a multi-year system

on the left on the right which I'm showing
is a was in one point zero schematic and

on the left is mine wasn't two point
zero which would have gone from a system

that used to be a four system to something
which is a suction system similar to

abandon what he had on the right
is you're going to have which

can be sucked within the suction system
and flow and the lead between the density

contrast is you have multiple layers
in one of those near the port helium so

it's air and air plus helium mixture so
that's why we are reducing the density

between the two fluids so if you do it and
it lets helium and you let it flow.

You start looking at
something which is a vortex

basically that you
are a late in life is a.

Good thing about this one is no I can
change I can run you would helium

I've gone to add one number zero point
seven five So I basically changed the they

didn't which previous work was that
they're gone to a very high number system

so that's what the main innovation in
this technique which we've got but

the other thing this weekend doing all
the time I was doing a lot of work with

the shot you can do a lot of the optical
diagnostic technique in this to understand

the dynamics of the flow.

Phone.

So we do that we see if I
can show you the real thing

from the real thing here there
are different control mechanism which you

have to there's a buffers the chair
there so you control it so

you basically start to experiment
with a very controlled velocity.

Very controlled for lots and so the match
the velocity if need be for the star.

There's not but we have done
an experiment where we wanted to know and

I would show some work on that
is when you have both here and

points it will start at what point
point C. dominates the flow I know that

buoyancy go this is it will dominate the
for at some point so we want to look at it

in the Richard Sambrook right at what
Richardson number is basically dominant.

Let me run the video so
you will see it's it's mashed or not.

So these are.

Two fluid such as running and you can see
that there may be a small difference but

it's not that large and you can be thin
look at OK what this year is going to be

so we can control this so
this is two fluids in B. and

the top one is basically you have air and
then here comes the helium in the bottom

and you start seeing the mix
becomes looks like that you split.

And since we're here let me play the other
one which will show you when we started

with the shear case.

So if you start with the sheer case.

And one sweep.

You'll see what happens to this year's
structure so I'll let you watch and

then I'll explain what's
going on in there.

So now he has put the helium on so the
controls on the helium could be turned on

because helium prices are very expensive
and in one experiment he ran a boat thirty

million tanks which is closer
to thousand dollars so

if your kids don't have a helium balloon
I can blame my graduate student.

So the good point about this one is
we have done this experiments for

like maybe two to three minutes and we
can sit in the flow feel a bit of a hard

time as women are different and
we can take studies Stickney study data so

this is a very studied stickle study
system that's that's the main point which

we're trying to drive.

So there's a sense of we have
different diagnostics we can look at.

Point measurement we can do
field measurements and we can do

like flow behind the field we can look at
all the what the structures are just so

the one sample image which we
have at a certain point and

these are basically the spikes you can see
the bubble and if you do the board it's

on till you can see that these are very
nice symmetric Spike Spike and

both of these were done for
low density countries so

this was the match with the water
experiment we wanted to make sure that

there is getting the same data
people have got for the water flows.

With him here's the difference between
if you do a low versus high density and

very low density contrast
along the centerline

you basically have very symmetry growth of
the system if you start going at a higher

density contrast you'll start seeing
that bubble is not rising that much and

Spike is falling falling down more so
the new writer will start looking at

is symmetry in the flow and the law is the
question why this is important why isn't

it because if you're following the system
and writing my question I'm writing for

the base flow system I have to know
where exactly is the makes clear to.

Where the mix layer is dominated more by
the spike which has a very large density

contrast than the bubble or not so
I can do a business approximation for

to get Does that make I need
to have of flow defined for

each Pedia of distribution what
the distribution looks like.

And we can start looking at that in a
different way to quantify the dynamics so

what I've done here is I've begun about
four hundred images these are backlit

system and we have seeded with this smoke
and then we can have a small point if

the done with the some kind of a trace
of what the depth will be what the B.S.

number of long term self absorption is
that's looking at the absorption technique

I can separate the height of
the bubble height of the spike and

if I think that gradient of this whole
this is going that's going to give you

the growth rates and it looks like as
they go in late time the growth rate for

the bubble falls down to be about
point zero four and there's a lot of.

Uncertainties given that is not
of jumping in the data which won.

So hard to get it basically
you have a winner when the.

If.

It's miss is going to be.

Quite easy.

And I'm writing you for it basically at
a spike and now I can take the difference

in my ears nothing but
in the Space X. from where you.

So this is just a different I'm doing for

there the data I would
need is what I am getting.

But no let's So that's where the global
mixing But now let's take a laser sheet

and start to the center plane and
look at what's going on in the structure.

So the cut through the center plane
we're seeing not a very nice smooth so

let me remind this before I go.

This is also sent a plane or
through with the very nice smooth

structure that you seem to flow from.

Not if you are to the plane.

You're not seeing a smooth structure
you're basically looking at some kind of

a dent right structure which is in Cup
interpenetrating in the different fluid.

So what happens is you can think
a board and the buoyancy drag system

the the light fluid which at the bottom
does not have enough inertia to

stop the heavy fluid which is coming down
so now it can penetrate and penetrate

more at least the small scale structures
on the edges of this that it is very large

element had most flow through in which
gets generated along the penetration This

is very similar when I did my shock to
both you saw this and the thing when for

the shell driven system we didn't see
a very nice spike you saw fragmented spike

so that was a very interesting
observation done in this flow and

what we did was we looked
at very close to this and

wanted to see OK Is there some kind of
uniform structure of this takes place and

if you do the Yeah it shows that the
structure is there a very much fragmented

so basically it's going to lead to very
large mixing along that line where you

have the spike structure but rest of
the flow going to be very mixed and

so it's going to be fuel fluid
which going to be there.

Why this wasn't interesting because in
point well and this is the result of

a just last year for twenty people there
was a paper which came out looking at.

Single mode so just a single bubble.

With a different.

Packages they did a simulation and they
saw that the penetration of these spikes

are much different depending on in
one case it was mixing quite a bit at

the early phase in the second one it kept
penetrating for a longer time so we were

not sure which model is the right model or
not and that's a single Morsi don't have

a neighboring elements which is affecting
the flow that's you're looking at single.

In the there was another paper going
to eleven which also looked at that but

that look for
multimode environment and this all.

This fragmented structure also and
the ball well Spike was very small in this

area so the whole controversy going on
is that really true or there's something

missing in the code so when we did the
similar experiments it looks like the fact

that it's such a very clear indication of
these kind of slow forward laws density

country all over these are not as drastic
as what these simulations are predicting

so it was not as Bostic that where
you're getting a very long tail but

a lot of small scale for this is which
is this looks like you're creating more

artificial gradients in the flow feed.

So once behind there do you
want to look at OK what's

what's going dominate in this world
in terms of and also to feed so

we did yesterday at the different
location I'm going to.

I'm showing these three different.

Notes.

And I'm showing these lines it just tells
you where the the full field I am so

flow is going from right to left so this
one is very early so you're looking at

very close to the split up late you
have already got in both you prime and

the plane and you prime is my stream
values and the prime is my cross string

systems across them is in the same
system where you have the radiation and.

As you move don't string you're
looking at the mixing Lee It

is this really moving down so
it's not centerline mixing there but

the maximum velocity for this system
has now shifted more to work but

the spike is so
it's more in the Spike dominated reason so

the shift of this is taking place in
the media was more to what the spike and

we have calibrated are different and
also some what it looks like and

the only thing that you're saying it's not
a very nice girls in the good bits and

on the center it's I don't I'm
a clear which is shifted towards

the bottom fluid.

The in this one.

So the.
One basically come in because the things

are very life so we're looking at about.

Twelve to sixteen inches the way we
are doing that if you're taking images of

the three different camera because we can
only look at small so three cameras and

he is stitching basically three
with one data two data and

three data that's why you're seeing that
and the match is fine you can see there

the way that's what's getting you.

And the next one was like OK if I want
to if I want to look at the system

the question is are we in the cells and
the regime is the flow has reached a point

where now I can drive these things and say
I'll fall for the floor will be this and

that and we've done only if you have a
cell similarity So we looked at you prime.

Fluctuation and we have basing
on the missionaries that there's

a number you infinity which came out
from buoyancy fractal creation we did so

we have come with this not domination
which appears that but that not my mind so

why didn't it flow has released into
something which looks similar flaw with

the late I mean this is very green and
black the late payment of loafing So

that's a very good thing because night say
is that we end statistically similar and

sell synergy so we plot the data that's
giving you very good information about

the flow field that's only in the stream
by seven or so is that true even for

crossing because that's my main
interest is so if we do the processing

look there OK yes it is true but the same
on demonstration we can do that in across

string but there's something else we
learned there if you were to do this.

There's value comes out to be your
own point seven point eight but

that if you have not demonstrated that you
in twenty four the fluctuation comes out

on one point five This tells you that
the contribution coming from the spike

side to this fluctuation is twice
more than the bubble side so

that the flow field has a much larger.

Changes in the velocity feed on
the spike and that is also true from

the images they saw a lot of different
structures which are created so

it looks like your bubble is going to have
a very nice smooth but also the feel and

it's moving up but Spike is a very
system which is not in the cells and

I want to send somebody has
a very large fluctuation for

most of the mixing will be coming
from your spike side of the field.

And you want to look at OK what
happens if I start looking at flow and

see the media distribution of this
different points in this system

at the center line
something ready have the.

Bubble fluid and something have the spike
food so we looked at three different and

just and if I do that the fluctuation
if you look at the center

it's looks like applied to it so
the chances of having a positive or

negative fluctuation means finding
spike at the center is uniform and

that's not at the center of the mix
there it's a cent over the maximum So

this is where over the math is one
that's what we call the center

of the mix here and
now they have shifted the things.

The other way to look at the same side
of sticks is to define the skewness And

if you look at the skewness and

produces of this flow that's going to give
you the same information so the kudos for

this flow if you have a boss in profile
skewness will be this is three that's

very similar to what we see for
the blue which represents your stream.

But if you start looking at
drawstring you're seeing a very large

eat in the flow and
on one that seems that you almost.

Spike side of the flow that's that's
all information which is telling us

it's giving you more information about
the nature of the dynamics of that flow

in the system.

But that's only one part of the story
that's only gives you the velocity is so

since we have this point please
measure mine and we have.

Then up and you would take me
where the helium in air so

let's see that one of the flow
feel the temperature so

what I mean by that is let's heat one of
the floor food by five degrees Celsius and

use so you said for
your temperature change identify

what they're mixing is and this is what
we're looking at different flow fields so

blue one is the more one which we want to
look at so that's where the center line

of the mix and you can see it's very much
uniform on the both side maybe this little

bit on the spike but it's not that
much different from the fluctuations.

And even for if I want to go up and down
these seems like a very much uniform so

if I look at just the density
feed it shows that the system and

on the center line is much more
uniform across the spike and

bubble so maybe we need to do
something else to figure out that So

let me jump to that what we want to do so
we wanted to look at an additional side to

stick so let's let's figure out at
the center line what some condition and

started sticks to define what's
the contribution of the Spike what's

the contribution of the bubble the way you
can do that it's like you can define that

all makes and look at B. and B.
priming that so so we looked at that and

this is the result which is coming
from here so you have defined the.

Fluctuation in both sides if I know you do
the contribution the fluctuations coming

from but one spike it appears that but one
has more fluctuations coming in the system

which was a little bit different than
when I had first said that you're most of

the fluctuation it looks like coming
in the post stream but and I said

the statement that point I made was maybe
the spike is driving on the fluctuation

but that's a little bit different I should
be more careful in saying that what it

tells me that but will my deal has not
mixed with the spike system but Spike some

of the mass of the spike as the double so
that mixing drives this to be higher year.

A fluctuation in your brain so

that's what we learned that if you combine
those two and you pull out your noble and

must like STEM so you get your rope right
in the prime you'll see the same thing is

a big spike it's just coming from you
know to both sides in the spikes and

they have equal contribution if you start
doing in this way so even though you have

an asymmetric flow feel country Bhushan
from but when that spike in that.

Is equal if I identify
that in this problem so

although I have a system which is very
large but the time to Bishan is sitting.

In that machine how much time have.

You so the other problem which we did was
that's one part of the story where we have

identified so far that you have to look
at these contributions coming from

the spike in both separately we
have additional statistics and

if I what's the contribution done
by the spike what's on the bubble.

Then we look at this problem at
the low density countries so

I went back to the water tunnel and
we added a flap put at the entrance so

at the beginning of this very
you have the flu or fluid and

cold fluid coming in there's a flap and
flap and basically a flap but

a different order Beijing and
that seats but.

Then I'm a big wig so

that's not a basically a dynamic it's a
dynamic perturbation it's not a static but

the vision which you're putting in we
want to look at OK if I put up this and

somehow I can change this perturbation to
have one more two more three more look

at what basically is driving in the early
phase where the more appealing was for

this experiment I was only interested
in understanding the dynamics and

the early phase of the system.

The way we are doing this hot and
cold water and

you have very similar to
the water to a guest and.

These are some of the might is that
just coming from the lips of you have

seeded with the road in six you die and
you have a laser coming from the bottom.

Top one is when you have no flap so
no flap means flap is stagnant and

you have the flow coming in.

That's your.

Next one is when you're flapping it
with a very small they haven't and so

they've done this two centimeter in that
case and if you see the difference between

that is not that much which means I'm
still in a region where the dominant mode

in this case is either large it already
put into that system that's all it's

telling me if I was trying to find out
what's the dominant mode which we have so

we did this experiment to find out
the dominant mode was about three point

seven centimeter for the end based
upon your spike based upon your

plate thickness as well as what
are the measures you have before that.

So now I went to a very large system so
I wanted to put a big very large and

then add to a system and clear on
stooping so what I want to play it

on is does the phase angle between
these modes have some impact so

one of the when I did the math analysis
it shows that if I do phase angle

zero to one the I can make this or
dancing what it says so that's that's what

I was trying to look at is that
something which I can look at this.

For this is the eight
centimeter he added two and

then let's move to what happens if you
start three more five more than if you

start adding the number of modes which
are very close to the smaller vehicle and

they will basically big down
the large payment structure and

then train when will we look very
similar to the eight centimeter but

the mix which is happening in the system
will be driven by the small skates

which makes sense because you
can buy the large scale but

you're mixing is very by the small scale
which are comparable in the energy so

you can basically mix with the engine and
we're still working on more so

we have done this in the broadband versus
we have done some analysis looking at

what's the flow feel is right close to the
system can we define what the vorticity is

what the initial deposit and because this
is not a pure relate in a problem you have

to understand you have a created because
you're putting the slab so we have to.

We have to quantify that and
to be coming from just you know fly.

Motion what's coming from the.

So that.

In this case it's this one is
coming from the hip sharing

that's where you're seeing
this very large so.

Yes we did the purity analysis for this so

we have data I know where we can quantify
what's the contribution coming from

related was the contribution coming
from shedding of that what it is.

And that's not something
which I'm talking about but

looking back to more the church talked
about before it was if you're going back

to the gas if I started that
she had an buoyancy boat.

So that's a problem of that you just you
were there later lesser there's no Shia

this is us here and this is where the
combined thirty looks like at the early

phase it looks very similar to only and
late times it is something similar to

the late in a phase and a lot of
the growth and I did some analysis on that

there is said OK let's figure out
what happens for D.H. over D.P.

So we just differentiated there and
it appears that if you have a very late in

the it would be if I do that becomes
a function of teeth Richard Believe me

a growing function if you're happy or
she or it should be a constant system and

if you combine that it shows that it's
a constant that starts moving toward

something that appears there might be
something going on in this reason and

I don't want to call it transition but
this something looks like flow goes from

dominated by here to dominated by buoyancy
so let's look at criteria which can be

used to point to fight there so they went
to the criteria for charts a number which

quantify is the amount of potential
energy versus the kinetic energy

have in the system at that point and
we did describe it in appears that

four different things we changed it into
all these in the Richardson number around

minus one point five to two point five
where this transition takes place and

we did this for the different numbers.

With that said it means
like you can write this

in a very simple form a bit out there
that he would define the time to come.

From you and Alfred you describe which
is the contribution coming from you

want to see a different system.

And then we're going to head and
look at different things but

our lot show this to let's
show something which.

Is very interested in which we phone so

since we had the data from other Shia
cases and and buoyancy pushchair cases and

wanted to look at more in the analysis
what is the kind of the energy generated

in the flow versus the potential energy
are we reaching some kind of cells and

that is that the dissipation and
energy will be a constant from value so

that's what they're trying to look at so
the only hard data for you and the so

I said OK spam values that action
should be very similar to the stream

bias because there's nothing happening so
they should look similar in this book so

I made that what they were
getting from my stream bodies but

the spine was equal and that used to
calibrate the kinetic energy potential

energy I just integrated the energy
across the mix layer which we have so

that gives me the potential energy and
I wanted that.

Different without any fear so
when I say as you know here I'm

increasing the density contrast density
contrast if you look at it in there

you know a potential energy is going to
be a constant value both point six years

which means your dissipation is aboard
point three three so that's what it's

coming out to be in normally a low density
contrast you're looking this up one point

four You point five That was something
which you saw that the dissipation

has decreased because the industry is much
larger it's basically creating more and

more scales but still at the early phase
of dissipating has not happened at that

large scale which we have and also second
thing maybe you have to look at is

potential energy is very large because
the density countries which have so

this a patient potential energy at
large flows is a value of a boat point

three three that's what we saw in
this case we then the same thing and

we did this analysis for what happens if
you have sheer and buoyancy combined.

If you have sheer important seat.

I'm buying it appears at very late
I mean the kind of big energy but

you have in the system over kinetic energy
of leaves a potential at least goes

to about a value zero point three five
which means dissipation is much larger in

that case the dissipation comes out to be
able to point six three and that is seems

to be right because all the initial kind
of energy which are given in the flow has

now dissipated at the late time and that's
where dissipating was large at that point

for that's what because we're
going to be on standby you know.

If we stop that's one of the main thing
which we saw was that the kind of energy

dissipation system gives you about
point three six point three seven

depending upon what we have.

And if I have one minute let me show
because they're due to talk to them so

I think some of this would do
is to take the same problem and

not shock it with a high so
we can basically run experiments at

very high mark numbers so we're looking
at Mach number three it's the point.

In the way I've done this experiment
is they have designed a new system

to go at any angle and the reason I wanted
to go in the angle was if you look at your

better clinic talk there's a cross-product
there so the question was asked if this

is a cross-product Why not just Gene the
angle very you have same pressure gradient

same density gradient and But amount of
energy deposited by claiming that angle

then this is the make I incline interface
in planning to if it will look like

something like a triangle if you have
a shock when I come from left to right and

then claim into phase which is created by
flowing a light guess from the top heavy

guess from the bottom it's nice at the
start mission and the start mission plane

I'm basically taking a suction board which
takes the floor we can control the amount

of diffusing which happens by controlling
the eight at which this action.

And it's a good experiments in this case
because we can only quantify them on.

Here production in this case from coming
from the shot as coming from the.

The momentum of this Wolf.

And these are some of the world which we
are doing we have a lot of data which

we have done and is a very interesting
because we're the only group which we can

do non-simultaneous density but
also at him as a Marine at these high and

high density controls for
a number of experiments so

I'll stop at that I will
I'll take any questions.

Yes.

So it so if you do.

And I'm just looking at their fluid
which is which is the fluid in

the Now What is a hot fluid it's going
to be a seam really in steady and

the density countries because
of that temperature is small

you're going to see very
uniform when it's very uniform.

But if you know make this a very large
lake a structure which is a very

high heat it full system then you're
not going to see a very uniform so

if you want to see something like the
the heart fluid which is falling in and

looks like a spike it's basically
like a finger which is happening.

So we can do baking waves right now.

So what we can do in this
in water is a very tough

challenging because of the surface
tension of the things which

takes place in most of these experiments
they're not more expensive water they

mostly dealing with either
two fluid which are.

An air and something which is.

A.

Simulation can be done.

Yes.

So that's where we got the idea so
it's a number of ideas as well as

you could partition of this energy for
accounting and

you put and came from I was looking
at the literature in oceanography So

that's how I got the idea to like
OK let's let's define something and

define the energy which is coming from
the kind take an educated and potentially

educated and separate them out for
some hall figure out what's coming from.

And take an idea which I have to something
which is generated in the cross train

direction because of
the gravitational field.

We don't we don't.

Know so so so
what we have is like what we did recently.

So.

We looked at this data in terms of
a thirteen point early phase we did hard

wired as a means for all the components
and we looked at what the more the company

does hold their braking and changes
their different spaces and then we did

the auto correlation between them to see
what it was spreading in the energy or

things were changing the board company
that's only one which we have done so

far in terms of understanding what
exactly is happening in terms of more

the company.

You.

Have to so
this is growing if you make this small and

small base you want to grow at that
point of funding going to happen

you won't be able to move so
you need to move it so

you can see it but the only thing which we
are doing with the conviction is in a box

system I can stand outside the box and
I can look at was things are going but

in that system like we have in the convict
I need to convict the whole thing so it's

a convention speech should not matter if I
can make it very fast I reduce my pain but

I can record very small defang going to
have become a big mix going to happen and

when I heard the.

You know.

So that that's.

So so we don't see any.

We don't see any something in this.

So.

We do.

That Rick Yes So basically
the self-sustaining flow for what's coming

from each of these structures if we think
about it only point what you have is you

know have you food it's been trading down
your light food and then they're basically

creating a shit in the system that
the South sustaining mechanism.

So what we expect is if I go very late and
in this case that dissipate help

attention it came out to be around the
point three three it should increase and

it should be about what kind of energy
dissipation should come out to be one so

then it becomes its own energy but
I don't think for

that to happen we probably have to go
very long so that would only be true if

your decision skills are very very large
and very small and you have very large

Lenski which I created in the large
number of Mortes which you have.

So we're looking at sort of seven
Live gives you the model of mixing.

Yes So.

Since you are from the.

So what do you can do is once you have the
live data you can basically define bank

words while it makes impediment at data
space it tells you how much is the mix and

haul much is the unmixed and if you're
big that they show that it will give you

the made up images of your base you
look at it up and with the protein and

since we also did the point that
made with this heated system so

we have point might have very large flock
to it so we have a very large a slow

fill environment they eat at their data
was collected because acetone is only

giving you one image is a true image
is this not a very large data sets.