Physics of Fluids,
Journal Year:
2025,
Volume and Issue:
37(1)
Published: Jan. 1, 2025
Qualitatively
evaluating
the
fundamental
mechanical
characteristics
of
square-fractal-grid
(SFG)-generated
turbulent
flow
using
piezoelectric
thin-film
flapping
velocimetry
(PTFV)
is
rather
time-consuming.
More
importantly,
its
sensitivity
in
detecting
high-frequency,
fine-scale
fluctuations
constrained
by
high-speed
camera
specifications.
To
reduce
dependency
on
imaging
future
PTFV
implementations,
regression
models
are
trained
with
supervised
machine
learning
to
determine
correlation
between
piezoelectric-generated
voltage
V
and
corresponding
local
equivalent
velocity
fluctuation.
Using
tip
deflection
δ
data
as
predictors
responses,
respectively,
Trilayered
Neural
Network
(TNN)
emerges
best-performing
model
compared
linear
regression,
trees,
support
vector
machines,
Gaussian
process
ensembles
trees.
TNN
from
(i)
lower
quarter,
(ii)
bottom
left
corner,
(iii)
central
opening
SFG-grid
provide
accurate
predictions
insert-induced
centerline
streamwise
cross-sectional
lateral
turbulence
intensity
root
mean
square-δ,
average
errors
not
exceeding
5%.
The
output
predicted
response,
which
considers
small-scale
across
entire
surface,
better
expresses
integral
length
scale
(38%
smaller)
forcing
(270%
greater),
particularly
at
corner
SFG
where
eddies
significant.
Furthermore,
effectively
captures
occasional
extensive
excitation
forces
large-scale
eddies,
resulting
a
more
balanced
force
distribution.
In
short,
this
study
paves
path
for
comprehensive
expedited
dynamics
characterization
detection
via
PTFV,
potential
deployment
high
Reynolds
number
flows
generated
various
grid
configurations.
Physics of Fluids,
Journal Year:
2024,
Volume and Issue:
36(9)
Published: Sept. 1, 2024
This
study
investigates
the
three-dimensional
(3D)
wake
transition
in
unconfined
flows
over
rectangular
cylinders
using
direct
numerical
simulation
(DNS).
Two
different
cross-sectional
aspect
ratios
(AR)
and
Reynolds
numbers
(Re)
are
scrutinized:
AR
=
0.5
at
Re
200
3
600.
The
investigation
focuses
on
characterizing
flow
patterns
forecasting
their
temporal
evolution
utilizing
proper
orthogonal
decomposition
(POD)
technique
coupled
with
a
long
short-term
memory
(LSTM)
network.
DNS
results
reveal
emergence
of
an
ordered
mode
A
for
3,
attributed
to
stabilizing
effect
elongated
AR.
On
other
hand,
case
smaller
(=
0.5)
exhibits
mode-swapping
regime
characterized
by
modes
B's
distinct
simultaneous
manifestation.
spanwise
wavelengths
B
approximately
4.7
1.2
D
0.5,
while
wavelength
is
3.5
3.
POD
serves
as
dimensionality
reduction
technique,
LSTM
facilitates
prediction.
algorithm
demonstrates
satisfactory
performance
predicting
patterns,
including
instabilities
B,
across
both
transverse
directions.
employed
adeptly
predicts
pressure
time
series
surrounding
cylinders.
duration
training
only
about
0.5%
required
computations.
research,
first
time,
effectiveness
POD–LSTM
complex
3D
instantaneous
past
Physics of Fluids,
Journal Year:
2022,
Volume and Issue:
34(7)
Published: July 1, 2022
Fluid–structure
interaction
analysis
has
high
computing
costs
when
using
computational
fluid
dynamics.
These
become
prohibitive
optimizing
the
fluid–structure
system
because
of
huge
sample
space
structural
parameters.
To
overcome
this
realistic
challenge,
a
deep
neural
network-based
reduced-order
model
for
is
developed
to
quickly
and
accurately
predict
flow
field
in
system.
This
network
can
at
next
time
step
based
on
current
motion
conditions.
A
be
constructed
by
combining
with
dynamic
solver.
Through
learning
structure
evolution
different
systems,
trained
systems
parameters
only
initial
Within
learned
range
parameters,
prediction
accuracy
good
agreement
numerical
simulation
results,
which
meet
engineering
needs.
The
speed
increased
more
than
20
times,
helpful
rapid
optimal
design
systems.
Physics of Fluids,
Journal Year:
2022,
Volume and Issue:
34(8)
Published: Aug. 1, 2022
Computational
fluid
dynamics
using
the
Reynolds-averaged
Navier-Stokes
(RANS)
remains
most
cost-effective
approach
to
study
wake
flows
and
power
losses
in
wind
farms.
The
underlying
assumptions
associated
with
turbulence
closures
are
one
of
biggest
sources
errors
uncertainties
model
predictions.
This
work
aims
quantify
model-form
RANS
simulations
farms
at
high
Reynolds
numbers
under
neutrally
stratified
conditions
by
perturbing
stress
tensor
through
a
data-driven
machine-learning
technique.
To
this
end,
two-step
feature-selection
method
is
applied
determine
key
features
model.
Then,
extreme
gradient
boosting
algorithm
validated
employed
predict
perturbation
amount
direction
modeled
toward
limiting
states
on
barycentric
map.
procedure
leads
more
accurate
representation
anisotropy.
trained
high-fidelity
data
obtained
from
large-eddy
simulation
specific
farm,
it
tested
two
other
(unseen)
distinct
layouts
analyze
its
performance
cases
different
turbine
spacing
partial
wake.
results
indicate
that,
unlike
data-free
which
uniform
constant
entire
computational
domain,
proposed
framework
yields
an
optimal
estimation
uncertainty
bounds
for
RANS-predicted
quantities
interest,
including
velocity,
intensity,
Green and Low-Carbon Economy,
Journal Year:
2024,
Volume and Issue:
unknown
Published: March 11, 2024
Hydrogen
is
a
nearly
emission-free
energy
carrier
with
many
enticing
qualities,
including
wide
availability,
environmental
friendliness,
and
high
calorific
value.
There
have
constantly
been
lot
of
challenges
to
establish
an
entire
fledge
low
carbon
hydrogen
economy
in
the
past
century.
This
study
aims
critically
analyse
economic,
environmental,
technological,
policy
implementation
division
low-carbon
find
novel
solutions,
bridging
gaps
giving
perspective
approach
study.
Differentiation
various
(LCH)
components,
green
blue
hydrogen,
was
also
proposed
based
on
life
cycle
assessment
emissions
(LCAE).
Current
perspectives
Promised
Pledged
Perspectives
are
considered
project
demand
2030.
A
thorough
economic
analysis
system
technologies
conducted
from
both
production
storage
by
comparing
systems.
Policies
towards
LCH
were
viewed
policymakers,
consumers,
R
&
D
perspectives,
through
which
several
challenges,
gaps,
keynote
necessities
stated.
Journal of Manufacturing Science and Engineering,
Journal Year:
2024,
Volume and Issue:
146(8)
Published: May 3, 2024
Abstract
Melt
pool
dynamics
in
metal
additive
manufacturing
(AM)
is
critical
to
process
stability,
microstructure
formation,
and
final
properties
of
the
printed
materials.
Physics-based
simulation,
including
computational
fluid
(CFD),
dominant
approach
predict
melt
dynamics.
However,
physics-based
simulation
approaches
suffer
from
inherent
issue
very
high
cost.
This
paper
provides
a
physics-informed
machine
learning
method
by
integrating
conventional
neural
networks
with
governing
physical
laws
dynamics,
such
as
temperature,
velocity,
pressure,
without
using
any
training
data
on
velocity
pressure.
avoids
solving
nonlinear
Navier–Stokes
equation
numerically,
which
significantly
reduces
cost
(if
generation).
The
difficult-to-determine
parameters'
values
equations
can
also
be
inferred
through
data-driven
discovery.
In
addition,
network
(PINN)
architecture
has
been
optimized
for
efficient
model
training.
data-efficient
PINN
attributed
extra
penalty
incorporating
PDEs,
initial
conditions,
boundary
conditions
model.
Machine Learning Science and Technology,
Journal Year:
2024,
Volume and Issue:
5(3), P. 035005 - 035005
Published: June 4, 2024
Abstract
This
study
aims
at
the
prediction
of
turbulent
flow
behind
cylinder
arrays
by
application
Echo
State
Networks
(ESN).
Three
different
arrangements
seven
cylinders
are
chosen
for
current
study.
These
represent
regimes:
single
bluff
body
flow,
transient
and
co-shedding
flow.
allows
investigation
flows
that
fundamentally
originate
from
wake
yet
exhibit
highly
diverse
dynamics.
The
data
is
reduced
Proper
Orthogonal
Decomposition
(POD)
which
optimal
in
terms
kinetic
energy.
Time
Coefficients
POD
Modes
(TCPM)
predicted
ESN.
network
architecture
optimized
with
respect
to
its
three
main
hyperparameters,
Input
Scaling
(INS),
Spectral
Radius
(SR),
Leaking
Rate
(LR),
order
produce
best
predictions
Weighted
Prediction
Score
(WPS),
a
metric
leveling
statistic
deterministic
prediction.
In
general,
ESN
capable
imitating
complex
dynamics
even
longer
periods
several
vortex
shedding
cycles.
Furthermore,
mutual
interdependencies
TCPM
well
preserved.
However,
hyperparameters
depend
strongly
on
characteristics.
Generally,
as
become
faster
more
intermittent,
larger
LR
INS
values
result
better
predictions,
whereas
less
clear
trends
SR
observable.