Breakup
of
an
axi-symmetric
ligament
of
ink
into
bubbles.
Ink
is
injected
with
an
oscillating
pressure
through
a
nozzle
of
20
diameter
into
a
tube
on
length
1 mm.
Physics and modelling
The
mathematical
model
used
in
this
simulation
is
the
two-phase
Eulerian
model,
where
the
phase-to-phase
interaction
is
modelled.
A
phase
fraction
()
describes
the
state
at
all
points
in
the
column:
0
corresponding
to
air;
1
to
ink.
The
ink
is
modelled
as
a
non-Newtonian
fluid.
Critically,
the
model
includes
surface
tension
for
the
air-ink
system.
Animations
The
animation
shows
the
pressure
oscillations
making
the
ligament
of
ink
to
form
peaks
and
troughs.
The
ligament
breaks
and
surface
tension
causes
spherical
droplets
to
form.
Note
that
the
first
droplet
is
an
amalgamation
of
two
peaks
since
the
first
peak
slows
down
due
to
air
resistance.
diameter
into
a
tube
on
length
1 mm.
(
)
describes
the
state
at
all
points
in
the
column:
0
corresponding
to
air;
1
to
ink.
The
ink
is
modelled
as
a
non-Newtonian
fluid.
Critically,
the
model
includes
surface
tension
for
the
air-ink
system.