Physics of Fluids,
Journal Year:
2023,
Volume and Issue:
35(12)
Published: Dec. 1, 2023
Flow-induced
vibration
of
a
rotating
cylinder
that
is
free
to
oscillate
in
the
stream-wise
and
cross
stream
directions
studied
laminar
flow
regime
via
linear
stability
analysis
(LSA)
direct
time
integration
(DTI).
LSA
reveals
instability
can
arise
from
fluid-,
elastic-,
or
coupled
fluid-elastic
modes
depending
on
rotation
rate
cylinder,
α,
reduced
speed,
U*.
Beyond
α=2,
U*-range
lock-in
increases
exponentially
with
an
increase
α.
DTI
brings
out
multiple
regimes
at
various
Each
extends
for
certain
range
U*
associated
different
mode
vortex
shedding.
The
differ
terms
number
pair
vortices
shed
during
each
cycle
oscillation.
amplitude
oscillation
vortices.
With
Re,
shedding
increase.
Vortices
are
generally
upstream
movement
while
shear
layer
wraps
around
it
resulting
large
lift
downstream
motion.
as
well
found
be
sensitive
initial
condition
α
A
discovered
where
three
distinct
response
states
realized
condition.
Hysteresis
flow,
respect
decrease
U*,
occurs
near
transition
between
desynchronization
switch
Ocean Engineering,
Journal Year:
2023,
Volume and Issue:
285, P. 115389 - 115389
Published: July 22, 2023
Recent
studies
of
passive
and
active
flow
control
devices
for
suppressing
vortex-induced
vibration
(VIV)
circular
cylinders
are
reviewed
extensively.
The
include
splitter
plates,
rods,
helical
strakes,
porous
layers
rough
surfaces,
the
jet
flow,
rotating
cylinder,
rods.
A
plate
with
a
certain
length
can
suppress
VIV
but
very
long
cause
galloping.
One
or
two
rods
located
downstream
separation
points
VIV.
suppression
using
three
to
eight
were
also
studied
increasing
rod
number
improve
effectiveness.
Porous
sufficient
porosity
thickness
achieve
nearly
full
generally
have
better
effect
than
surfaces.
Helical
strakes
well
when
its
pitch
ratio
is
greater
10
height
0.2
times
cylinder
diameter.
If
external
energy
used,
suppression.
Rotating
in
one
direction
but,
another
direction,
enhance
Some
important
conclusions
highlighted
section
4
this
paper.
Applied Physics Letters,
Journal Year:
2024,
Volume and Issue:
124(23)
Published: June 3, 2024
In
this
study,
we
propose
a
wind-direction
adaptive
piezoelectric
energy
harvester
employing
small
wing
passive
control
configuration
(WDEH-SW)
for
bidirectional
wind
harvesting.
Our
design
significantly
enhances
harvesting
capabilities,
addressing
the
limitations
of
traditional
harvesters
by
modifying
aerodynamic
characteristics
bluff
body
via
rotations.
Additionally,
introduce
criterion
determining
impact
direction
changes
on
efficiency.
Experimental
comparisons
with
conventional
galloping-based
and
vortex-induced
vibration-based
demonstrate
superior
performance
proposed
structure.
The
experiment
results
indicate
that
structure
effectively
adapts
to
in
direction,
thereby
preventing
significant
decrease
or
failure
Compared
unidirectional
harvester,
exhibits
34.6%
increase
1.63
μW
power
output,
an
overall
average
output
reaching
6.35
μW.
Notably,
WDEH-SW
shows
excellent
adaptability
high
both
medium
low
velocity
ranges,
providing
valuable
insights
designing
compact
harvesters.
This
study
showcases
promising
applications
self-powered
micro-devices,
particularly
straightforward
environments
such
as
car
train
tunnel
entrances
exits.
Physics of Fluids,
Journal Year:
2023,
Volume and Issue:
35(8)
Published: Aug. 1, 2023
A
circular
cylinder
attached
by
a
rigid
splitter
plate
of
different
lengths
was
tested
to
examine
its
effects
on
the
control
flow-induced
vibration.
Tests
were
carried
out
in
closed-loop
water
channel.
diameter
D
=
20
mm
and
mass
ratio
m*
≈
50
installed
oscillate
transverse
direction.
wide
range
length
considered,
i.e.,
L/D
0–3.5,
at
reduced
velocity
Ur
1–25
Reynolds
number
Re
800–11
000.
Numerical
simulations
also
conducted
reveal
flow
structures
associated
with
vibration
modes
observed
experiment.
It
is
found
that,
as
increases
from
0
0.25,
peak
value
oscillation
amplitude
appears
higher
velocities.
When
continues
rise,
galloping-type
oscillations
occur
0.5
0.75.
The
transition
stage
has
been
1.0.
Oscillation
then
significantly
suppressed
when
larger
than
1.5.
Physics of Fluids,
Journal Year:
2024,
Volume and Issue:
36(1)
Published: Jan. 1, 2024
A
novel
and
effective
hybrid
technique,
which
involves
active
surface
heating
strategies
in
conjunction
with
the
use
of
passive
splitter
plates
wake
cylinder,
is
proposed.
In
this
report,
we
present
results
a
numerical
investigation
on
two-dimensional,
laminar
mixed
convection
flow
over
circular
cylinder
hot
rigid
plate
attached
to
it
side.
projection
algorithm-based
finite
volume
method
employed
obtain
solution
coupled,
nonlinear
governing
partial
differential
equations
subjected
Courant–Friedrichs–Lewy
conditions.
The
isothermal
under
influence
gravity
field
generates
an
upward
buoyancy
force
cylinder.
For
different
length-to-diameter
(L/D)
ratios,
effect
aerodynamic,
wake,
heat
transfer
characteristics
has
been
studied
for
wide
range
parameters;
75
≤Re≤
150,
0
≤Ri≤
1,
0.5
≤L/D≤
1
at
Pr
=
0.7.
It
observed
that
would
bring
about
conspicuous
changes
such
as
asymmetry
vortex
shedding
behind
low
Reynolds
numbers.
outcomes
demonstrate
notable
improvement
convective
drag,
gains
up
7%
15%,
respectively.
found
rate
frequency
decrease
increase
L/D
ratio.
Correlations
estimation
Strouhal
number
Nusselt
have
also
proposed
helps
provide
more
thorough
understanding
thermal
aerodynamic
features
approach.
Physics of Fluids,
Journal Year:
2024,
Volume and Issue:
36(4)
Published: April 1, 2024
With
the
micro-miniaturization
of
offshore
wireless
sensors,
signal
lights,
and
other
devices
emergence
problem
self-powering
in
distant
sea,
how
to
harvest
energy
from
low-speed
currents
has
become
a
hot
spot
research
nowadays.
To
improve
output
power
conversion
efficiency
water
flow,
we
propose
vertical
cantilever
beam
circular
cylinders
fitted
with
rigid
splitter
plate
piezoelectric
harvester
(CSPPEH).
In
this
paper,
influence
length
attack
angle
on
CSPPEH
been
experimentally
investigated.
The
vibration
response
mechanism
involving
mutual
transition
between
vortex-induced
galloping
was
analyzed
through
particle
image
velocimetry
flow
field
visualization.
experimental
results
indicate
that
characteristics
increase
initially
then
decrease
plates
(L/D
=
0–2.4)
at
0°,
which
can
be
explained
by
theoretical
model
harvester.
It
is
found
optimal
occur
1.40D
an
90°.
maximum
values
for
amplitude,
swing
angle,
voltage,
power,
density
are
4.96D,
21.7°,
42.68
V,
910.81
μW,
1.94
mW/cm3,
respectively.
Efficiency
up
2.2%
0.4D
90°
plate.
Compared
bare
cylinder
harvester,
significantly
improved.
demonstration
continuous
charging
discharging
capacitors
light
emitting
diode
lights
performed
show
practicability
designed
CSPPEH.
Overall,
present
study
enables
applications
realizing
self-powered
sensing
under
low-water-speed
environments.
Physics of Fluids,
Journal Year:
2023,
Volume and Issue:
35(8)
Published: Aug. 1, 2023
In
this
study,
we
introduce
a
novel
arrangement
consisting
of
two
arc
plates
around
cylinder
with
the
privilege
improved
fluid
flow
and
noise
control.
The
are
placed
symmetrically
concentrically
at
rear
portion
circular
cylinder.
coverage
angle
(30
°≤β≤75°)
normalized
radius
(1.125≤Rd≤1.625)
varied
to
find
optimum
case
in
terms
drag
reductions.
simulations
performed
for
turbulent
Reynolds
number
22
000.
numerical
analysis
is
based
on
an
unsteady
Reynolds-averaged
Navier–Stokes
(URANS)
solver
Ffowcs
Williams
Hawkings
(FW–H)
acoustic
analogy.
It
found
that
by
implementing
plates,
level
coefficient
decrease
dramatically.
results
also
reveal
strong
correlation
between
vortex
shedding
suppression
reduction.
shown
as
fluctuation
lift
force
decreases,
performance
control
enhances
simultaneously.
Furthermore,
assessment
indicates
specific
configuration
overall
sound
pressure
decreases
51
dB
compared
uncontrolled
no
plates.
Also,
maximum
reduction
27
achieved,
which
reduces
39%
conclusion,
provide
support
proposed
passive
method
beneficial
strategy
wake
cylindrical
structures,
have
wide
applications
industry.
Physics of Fluids,
Journal Year:
2023,
Volume and Issue:
35(4)
Published: April 1, 2023
The
enhancement
of
flow
induced
vibration
a
circular
cylinder
by
rotating
control
rod
is
investigated
through
two-dimensional
numerical
simulations.
Reynolds
number,
diameter
ratio,
and
gap
ratio
are
150,
0.2,
respectively.
Simulations
conducted
for
two
position
angles
β
=
90°
135°,
rotation
rates
ranging
from
0
to
6,
reduced
velocities
between
1
20.
response
the
cylinder–rod
system
at
has
lock-in
regime
where
amplitude
high
frequency
stops
increasing
with
increase
in
velocity
linearly.
For
exceeding
2,
increases
enters
lower
boundary
velocity.
It
remains
until
largest
studied
20;
as
result,
higher
cannot
be
determined.
large
amplitudes
repeats
cyclically
after
every
or
more
periods.
As
combined
wake
modes
found:
2S/P
+
S
2P/P
S.
In
mode,
changes
one
mode
another
within
each
cycle.
receives
power
fluid,
gives
fluid
although
net
exchange
whole
zero.
