This
paper
examines
the
impact
of
two
tandem
configurations
ellipsoids
on
laminar
flow
using
numerical
methods.
The
first
configuration
features
an
ellipsoid
in
a
prolate
orientation,
while
other
employs
tilted
at
45°
angle
relative
to
vertical
axis.
study
investigates
inter-ellipsoid
distances
ranging
from
one
diameter
(1D)
eight
diameters
(8D)
ellipsoids'
centers
and
different
Reynolds
numbers
(100,
200,
300,
400).
presented
results
focus
hydrodynamic
forces,
wake
symmetry,
patterns
for
scenarios.
findings
reveal
that
when
is
present
ellipsoid,
drag
forces
between
front
rear
tend
approach
smaller
separations
compared
orientation
case.
In
these
cases,
separation
asymmetric
x–y
plane
but
becomes
symmetric
x–z
larger
spacings.
Additionally,
detachment
zones
are
analyzed
concerning
number.
It
observed
up
distance
approximately
4D,
significantly
influences
recirculation
hydrodynamics
ellipsoid.
The
vibration
responses
and
flow
dynamics
in
the
vortex-induced
vibrations
of
two
near-wall
flexible
cylinders
tandem
arrangement
are
investigated
through
three-dimensional
direct
numerical
simulations
with
spacing
ratio
s/D
=1.5–6
(D
=
diameter
cylinder),
gap
G/D
0.8,
cylinder
length
25D,
Reynolds
number
500.
in-line
(IL)
crossflow
(CF)
predominated
by
first-order
mode
along
span.
upstream
oscillates
at
a
higher
CF
amplitude
than
downstream
one,
maximum
IL
amplitudes
both
smaller
those
single
cylinder.
dominant
frequencies
oscillation
identical
for
cylinders,
they
larger
that
mean
drag
rms
occur
on
counterpart.
difference
between
spanwise
lift
reduces
as
increases.
Different
types
observed
cylinders:
1.5–2,
an
“extended-body
regime”
“reattachment
excited
near
two-ends
middle
regions
span,
respectively;
3,
reattachment
regime
“co-shedding
appear;
4–6,
co-shedding
is
but
different
vorticities
related
to
amplitudes.
At
wall
proximity
induces
multi-frequencies
oscillations,
compared
single-frequency
oscillations
wall-free
conditions.
lower
Weak
“2S”
typical
2S
vortex
shedding
patterns
conditions,
respectively.
The
flow
behind
nine
different
arrays
of
cylinders
is
experimentally
investigated
via
Particle
Image
Velocimetry
(PIV)
at
a
Reynolds
number
Re
∼100
based
on
the
diameter
cylinders.
Each
array
consists
column
four
in
front
and
three
rear.
horizontal
distance
between
two
columns
vertical
within
each
are
varied
for
H/D=[2,4,8]
V/D=[2,4,6],
resulting
denoted
as
mVnH,
where
m
corresponds
to
V/D
n
stands
H/D.
PIV
measurements
conducted
15
s
200
Hz
frequency,
corresponding
39
360
vortex
shedding
events
wakes
this
study.
Then,
proper
orthogonal
decomposition
applied
velocity
fields
analyze
dynamics.
All
show
unsteady
flow,
their
structures,
they
classified
main
categories
single
bluff
body
(SBB),
transitional
(TR),
co-shedding
(CS)
flow.
SBB
characteristics
can
be
seen
2V2H
2V4H
arrays,
but
latter
has
more
steady
H/D
increases
from
2
4.
2V8H
4V2H
have
an
asymmetric
with
several
streets
act
intermediary
stage
shift
CS
structure
when
distances
increased.
highest
total
kinetic
energy
values
widest
probability
density
functions
components
observed
group.
five
remaining
group
symmetric
or
present
behind.
However,
distances,
frequency
phase
synchronization
change
considerably,
which
might
important
effect
on,
example,
heat
transfer
structural
load
This
paper
numerically
investigates
the
influence
of
a
fixed
downstream
control
cylinder
on
flow-induced
vibration
an
elastically
supported
primary
cylinder.
These
two
cylinders
are
situated
in
tandem
arrangement
with
small
dimensionless
center-to-center
spacing
(L/D,
L
is
intermediate
and
D
diameter).
The
present
two-dimensional
(2D)
simulations
carried
out
low
Reynolds
number
(Re)
regime.
focus
this
study
to
reveal
underlying
flow
physics
behind
transition
from
vortex-induced
galloping
response
due
presence
another
Two
distinct
field
regimes,
namely,
steady
alternate
attachment
observed
for
different
L/D
Re
values.
Depending
evolution
near-field
structures,
four
wake
patterns,
“2S,”
“2P,”
“2C,”
“aperiodic,”
observed.
corresponding
upstream
characterized
as
interference
extended
vibration.
As
ratio
increases,
lift
enhancement
seen
be
weakened.
detailed
correlation
between
force
generation
near-wake
interactions
investigated.
findings
will
augment
our
understanding
reduction
or
energy
harvesting
cylindrical
structures.
In
natural
convection
(high
Richardson
number
Ri),
a
high
Prandtl
(Pr)
leads
to
thinner
thermal
boundary
layers,
enlarging
the
gradient
and
hence
enhancement
of
buoyancy
effect.
forced
(low
Pr
introduces
thicker
velocity
layers.
mixed
scenarios,
where
both
are
significant,
interaction
between
Ri
determines
resultant
flow
pattern
heat
transfer
characteristic.
Three
tandem
circular
cylinders
with
an
identical
spacing
ratio
4.0
in
flows
were
numerically
investigated
by
using
finite
element
method.
The
computations
carried
out
range
=
5–50
0–2
at
low
Reynolds
Re
150.
results
squared
strain
rate
vorticity
shed
light
on
enstrophy
process.
Thermal
plume
structures
far
wake
originate
from
upper
dispersed
vortices
due
superimposed
Pr,
while
they
suppressed
Pr.
increase
plays
role
as
stabilization,
growth
reverse
role.
time-averaged
velocity,
pressure
coefficient,
temperature
become
more
asymmetrical
Ri.
Nusselt
upstream
cylinder
is
approximately
equal
empirical
result
without
consideration
buoyancy.
Due
buoyancy,
migration
shear
layers
along
surface
frequency
alteration
harmonic
drag,
lift,
coefficients.
Wake
transitions
of
flow
past
two
tandem
semi-circular
cylinders
near
a
moving
wall
were
numerically
investigated
using
the
lattice
Boltzmann
method
at
Reynolds
number
150
with
various
gap
ratios
(G/D,
where
G
and
D
are
spacing
between
cylinder
diameter,
respectively)
(L/D,
L
is
distance
centers).
The
analysis
aims
to
clarify
effects
L/D
G/D
on
wake
structures,
hydrodynamic
forces,
Strouhal
number,
spectral
energy
exerted
both
cylinders.
This
study
reveals
five
distinct
regimes
in
L/D-G/D
space,
such
as
overshoot,
continuous
reattachment,
pair-wise,
quasi-coshedding,
coshedding.
These
identified
plots
vorticity
contour,
time
history
drag
lift
coefficients
(CD
CL),
power
density,
proper
orthogonal
decomposition
fluctuation
into
deterministic
spatial
structures.
Furthermore,
regime
maps
diagrams
time-averaged
pressure
surface
given
analyze
influence
wall.
A
significant
change
CD
CL
observed
for
cylinders,
depending
ratios.
coefficient
downstream
remarkably
lower
than
that
upstream
cylinder.
increase
when
small
due
near-moving
effects.
root-mean-squared
value
result
proximity
effect.
Meanwhile,
remains
mostly
same.
This
study
aims
to
explore
wind
load
interference
effects
on
tandem
photovoltaic
(PV)
panels,
focusing
inclined
angles
(α)
and
gaps
(X/L).
Conventional
models
often
struggle
capture
nonlinear
airflow
dynamics
that
drive
these
effects.
To
address
this
limitation,
the
research
introduces
a
novel
approach
analyze
complex
spatiotemporal
evolution
of
phenomena
in
PV
panels.
A
quantitative
analysis
was
conducted
using
high-order
Koopman
Mode
Decomposition
(HOKMD)
method.
method
integrates
components,
enabling
precise
identification
dynamic
modes
coherent
structures.
evaluates
synchronous
vorticity
pressure
fields,
fluid
forces,
power
spectra
panels
under
varying
α
X/L.
The
results
demonstrate
for
α>25°
X/L<2.0,
are
highly
pronounced,
while
X/L>2.0,
significant
shielding
observed
downstream
panel.
It
revealed
two
dominant
modes,
providing
new
insights
into
patterns
vortex
interactions
traditional
linear
fail
capture.
application
HOKMD
accurately
captures
characteristics
flow
around
findings
advance
understanding
provide
valuable
optimizing
design
improve
structural
stability
durability.
Journal of Fluid Mechanics,
Год журнала:
2025,
Номер
1008
Опубликована: Март 28, 2025
We
perform
simulations
of
a
two-fluid–structure
interaction
problem
involving
liquid–gas
flow
past
fully
submerged
stationary
circular
cylinder.
Interactions
between
the
interface
with
finite
surface
tension
and
disturbances
arising
from
cylinder
induce
variety
interfacial
phenomena
wake
structures.
map
different
regimes
in
parameter
space
defined
by
Bond
number
$Bo
\in
[100,
5000]$
submergence
depth
$h/D
[1,
2.5]$
while
keeping
Reynolds
(
Re
)
Weber
numbers
fixed
at
150
1000,
respectively.
The
emerging
features
are
classified
into
three
distinct
regimes:
waves
generated
Strouhal
vortices,
entrainment
multi-scale
gas
bubbles
reduced
deformation
state.
In
wave
regime,
we
demonstrate
that
frequency
transverse
fluctuations
specific
streamwise
location
is
identical
to
vortex
shedding
frequency.
Additionally,
wavelength
determined
size
pairs
consisting
alternating
vortices.
regime
$
Bo
=
1000$
,
our
bubble-size
distributions
reveal
entrained
have
sizes
ranging
one
two
orders
magnitude
smaller
than
These
formed
primarily
through
plunging
surfing
breakers
2.5$
.
contrast,
1$
initially
emerge
breakup
finger.
Over
time,
some
these
grow
coalescence
cascades.
influence
[50,
150]$
[700,
1100]$
on
quantified
terms
mean
bubble
count.
Lastly,
how
deformability
drives
hydrodynamic
lift
force
acting
net
downward
materializes
only
due
broken
symmetry
front
stagnation
point.
While
study
focuses
two-dimensional
simulations,
also
provide
insights
three-dimensional
mechanism
for
extreme
cases
