The flow of some unique liquid

fluids are a necessary part of everyday
life after all without water you
couldn't live and without chocolate
syrup well what would be the point but
have you ever noticed that not all
liquids behave the same in fact some of
them do some pretty bewildering stuff
under the right circumstances and even
after decades of research scientists are
no closer to understanding why one
question about strange fluids
may have
finally been answered thanks to some
glass beads and i always love saying
this
laser beams
all liquids we encounter in the real
world can basically be boiled down to
one of two kinds they're either
newtonian or non-newtonian newtonian
fluids are pretty easy to grasp mean
not literally in some cases a newtonian
fluid like water would squirt right out
of your hand but chocolate syrup is also
newtonian even though it would slowly
dribble out of your hand maybe as you
frantically lick your palm to get all
that chocolatey goodness before it drips
away it's not just me right
uh anyway in other words chocolate syrup
is much more viscous than water
viscosity is a measure of a fluid's
resistance to flow it's basically the
friction between molecules in a fluid
the higher the viscosity the slower the
flow a newtonian fluid obeys newton's
law of viscosity which means its
viscosity is constant it doesn't change
when a force is applied to it
non-newtonian fluids on the other
less sticky hand
do change their viscosity which can lead
to some pretty zany shenanigans
there are different subcategories of
non-newtonian fluids depending on how
their viscosity changes there are
dilatance whose viscosity increases as
force is applied and examples of
dilatance include quicksand silly putty
and the cornstarch water mixture known
to first grade classrooms as oobleck
the tiny cornstarch particles in oobleck
can flow freely with the water molecules
if you gently dip your fingers in but it
you give it a good smack the cornstarch
locks up giving oobleck a surprisingly
solid character
you could straight up run across a
swimming pool if you dumped enough
cornstarch in it but
there are vandalism laws so you know
some fluids get more viscous when force
is applied but the opposite can also be
true ketchup is in a category of
non-newtonian fluids called
pseudoplastics when no force is applied
it just sits there not doing anything
but when you give the back of a bottle a
whack the viscosity decreases and the
ketchup comes out till R20%
inside the sauce at a molecular level
what's happening is long chains of atoms
called polymers get tangled together and
they hold fast but when they're smacked
or shaken they stretch out and align
allowing the gooey red paste to slide
around hopefully onto your french fries
but
probably a little on your pants too
still there are many more weird
non-newtonian behaviors scientists don't
have answers for they may have just
solved one riddle that stood for over 50
years the problem was first noticed in
the 1960s when engineers were attempting
to extract oil from the ground with
fluid that contained long chain polymers
pumping these so-called pressure fluids
into the ground below a certain rate
worked fine but pumping them faster
would cause them to become much more
viscous,
the fluids would only behave this way
when flowing through the microscopic
spaces between soil when not confined to
the twisty windy paths in a porous
medium the fluid's viscosity would
actually drop as more forces applied
like ketchup for a while scientists
thought that maybe the polymers were
clogging up the pores in the soil but
that couldn't explain how the fluids
flowed easily when the flow rate dropped
again
it wasn't until a new study was
published in late 2021 that scientists
think they might have cracked it part of
the problem they've had is soil and
other porous media aren't see-through so
it's kind of hard to tell what's going
on down there
to solve this they created a custom
medium out of glass beads and they
concocted a polymer solution with the
same refractive index as the glass
meaning the liquid and solid would both
bend light exactly the same way to see
the windy paths fluids would fall out in
the spaces between the beads the
researchers added a red dye to the
solution that would give off a certain
wavelength of light when hit with a
laser to visualize how the fluid was
moving they added tracer particles that
would emit a different color when
excited by another laser
with this extremely complicated setup in
place they observed the fluid flowing at
different rates and found that the long
polymers in it started tumbling around
as the fluid moved faster this movement
pushed on other nearby molecules in the
liquid and caused a phenomenon called
elastic turbulence creating eddies and
slowing the whole fuid
down.
The researchers think this new
understanding of why pusher fluids
suddenly become so viscous could be
useful for purifying groundwater
aid in the development of new polymer
containing solutions that can forcewater through rocks trapping
contaminants in the process but there's
more work to be done because elastic
turbulence itself isn't fully understood
maybe that'll be the next riddle solved
or maybe first we'll finally get an
answer for why people like ketchup on
scrambled eggs granted that has nothing
to do with its non-newtonian properties
but it's still something i just can't
wrap my head around.