Impinging jet ventilation: Mitigating influenza transmission through partition and exhaust layout optimization
Physics of Fluids,
Год журнала:
2025,
Номер
37(1)
Опубликована: Янв. 1, 2025
This
paper
investigates
the
transmission
characteristics
of
cough
droplets
from
infected
individuals
in
office
environments
under
influence
an
impinging
jet
ventilation
(IJV)
system
based
on
Eulerian–Lagrangian
model.
The
accuracy
dispersed
phase
model
and
IJV
simulation
was
validated
by
analyzing
a
single
droplet
evaporation
model,
publicly
available
experimental
results,
previously
simulated
results.
effects
different
exhaust
locations,
relative
positioning
to
individual,
application
partitions
spatial
propagation
are
explored.
results
indicate
that
exhibit
significant
ability
obstruct
capture
droplets.
Under
static
conditions,
they
capable
capturing
over
36%
generated
coughing,
although
this
efficiency
may
be
slightly
influenced
system.
notably
affects
movement,
with
progressively
converging
toward
upper-left
corner
room
as
airflow
develops.
exhausts,
combination
system,
is
crucial
impeding
removing
Taking
into
account
variations
individual's
position,
centrally
located
arrangement
might
provide
more
effective
inhibition
virus
dispersion.
Язык: Английский
Infectious cough droplet dynamics in a makeshift hospital isolation ward
Physics of Fluids,
Год журнала:
2025,
Номер
37(2)
Опубликована: Фев. 1, 2025
The
COVID-19
pandemic
highlighted
the
need
for
rapidly
deployable
healthcare
facilities,
leading
to
increased
use
of
modular
construction
methods.
Nonetheless,
knowledge
about
airflow
patterns
and
spread
bioaerosols
in
these
wards
remains
insufficient,
potentially
heightening
risk
cross-infection
among
workers
patients.
This
paper
presents
a
ventilation
design
negative-pressure
ward
aimed
at
reducing
infectious
particles.
We
investigate
effects
various
designs,
patient
postures
(sitting
supine),
air
changes
per
hour
(ACH)
on
cough
droplets
an
airborne
infection
isolation
room
using
large
eddy
simulation
Eulerian–Lagrangian
model.
Findings
show
that
ceiling
exhaust
grilles
(design
2)
resulted
lowest
radial
dispersion
(3.64
m)
12
ACH,
while
sidewall
exhausts
(baseline)
performed
best
higher
ACH
levels.
Seated
patients
had
quicker
droplet
evaporation
compared
those
supine
position.
setups
survival
included
bed's
bottom
ceiling,
maintaining
minimum
ACH.
Cases
5
13,
with
over
patient's
head
bottom,
showed
concentrations
DPM,
under
0.008
km−3
near
source
less
than
0.001
mid-room.
Sitting
posture
consistently
led
lower
DPM
concentrations.
research
emphasizes
critical
role
placement
re-circulation
transmission
risks,
ultimately
contributing
improved
strategies
control
AII
rooms.
Язык: Английский
The effects of ventilation layout on cough droplet dynamics relating to seasonal influenza
Physics of Fluids,
Год журнала:
2024,
Номер
36(11)
Опубликована: Ноя. 1, 2024
The
primary
aim
of
this
paper
is
to
investigate
airborne
virus
transmission
in
a
typical
meeting
room
relating
the
heating,
ventilation,
and
air
conditioning
(A.C.)
systems.
While
installation
4-way
cassette
A.C.
systems
offices
rooms
has
become
increasingly
common,
their
efficiency
mitigating
short-range
spread
remains
poorly
understood.
Addressing
gap
critical
post-pandemic
era,
where
understanding
limitations
various
ventilation
paramount
for
public
health.
We
systematically
compare
performance
A.C.,
configurations
mixing
displacement
systems,
natural
controlling
respiratory
viruses.
Our
research
uniquely
integrates
evaporation
models
accurately
simulate
cough
clouds'
multiphase
behavior
under
both
quiescent
thermally
influenced
conditions.
study
benchmarks
these
against
two
widely
recognized
standards
(i.e.,
5
changes
per
hour
10
l/s
person),
offering
evidence-based
insights
applicable
across
diverse
indoor
settings.
findings
reveal
significant
thermal
effects
case,
resulting
32.3%,
54.3%,
8.0%
axial,
vertical,
lateral
virus-laden
droplets,
respectively.
Notably,
0.5
m/s
system
demonstrated
superior
performance,
reducing
axial
by
29.6%
compared
other
mechanical
configurations.
Furthermore,
role
exhaust
outlets
or
doors
was
found
be
shaping
pattern
scenarios.
This
work
can
offer
practical
guidance
office
workers,
engineers,
health
officials
on
enhancing
infection
control.
Язык: Английский
Numerical simulation of high-concentration droplet flow in an idealized mouth–throat airway model in the influence of environmental temperature and humidity
Physics of Fluids,
Год журнала:
2024,
Номер
36(12)
Опубликована: Дек. 1, 2024
The
exchange
of
water
vapor
between
high-concentration
droplets
and
air
significantly
influences
droplet
deposition
in
the
upper
airway
model
during
nebulizer
use.
This
study
employed
a
two-way
coupled
Eulerian–Lagrange
method
to
quantify
nebulized
evaporation
relative
humidity
(RH)
variations
within
an
idealized
mouth–throat
(MT)
model,
utilizing
validated
numerical
models.
interaction
inhaled
was
computed
using
multiplier
based
on
particle
parcel
method.
Simulations
normal
saline
flow
inhalation
MT
were
conducted
under
two
environmental
conditions:
indoor
(26.5
°C,
RH
=
50%)
warm
wet
(30
75%),
with
various
rates
mirroring
previous
experiments.
Droplet
fractions
(DFs)
patterns
recorded.
results
indicated
that
DF
initially
decreased
then
increased
rising
rates.
largest
discrepancy
predicted
measured
DFs
10.86%.
These
findings
support
theory
balance
elevated
dictates
airway.
Additionally,
simulations
revealed
conditions
affect
DF,
up
20.78%.
hotspot
shifted
from
anterior
posterior
pharynx.
Язык: Английский
Gravitational Interactions of Two Small Evaporating Drops
Research Square (Research Square),
Год журнала:
2024,
Номер
unknown
Опубликована: Фев. 22, 2024
Abstract
Relative
trajectories
are
determined
for
a
pair
of
water
drops
falling
in
air
with
radii
between
2
μm
and
30
μm.
The
droplets
small
enough
that
diffusion
dominates
convection
evaporation,
but
significant
drop
inertia
at
low
Reynolds
number
is
considered.
In
addition
to
hydrodynamic
lubrication
forces,
attractive
van
der
Waals
forces
Maxwell
slip
taken
into
account.
Because
the
loss
mass
not
uniform
due
presence
second
drop,
transfer
momentum
effectively
decoupled,
droplet
position
needs
be
assessed.
Three
outcomes
compared.
isolated
result
both
employed
as
base
case,
since
constant
over
each
surface.
Alternatively,
bispherical
coordinate
solution
two
evaporating
applied,
positions
1)
fixed
by
hydrodynamics
or
2)
allowed
move
based
on
nonspherical
loss.
all
three
cases,
evaporation
leads
weaker
inertial
effects
stronger
effects.
single
sphere
model
has
largest
gap,
followed
solutions
movable
center,
respectively.
Critical
horizontal
offsets
coalescence
also
calculated
finite
vertical
offset.
With
molecular
slip,
approaches
lead
similar
results,
making
choice
method
nearly
inconsequential.
Moderate
agreement
previous
experiments
an
approximate,
generalized
form
current
theory
obtained
rate
drops.
Язык: Английский
Gravitational Interactions of Two Small Evaporating Drops
Aerosol Science and Engineering,
Год журнала:
2024,
Номер
9(1), С. 52 - 66
Опубликована: Июль 16, 2024
Язык: Английский
A novel and versatile cough simulator for respiratory disease studies
Physics of Fluids,
Год журнала:
2024,
Номер
36(12)
Опубликована: Дек. 1, 2024
The
COVID-19
pandemic
has
highlighted
the
critical
need
for
comprehensive
studies
on
respiratory
diseases,
particularly
those
focusing
human
coughs
as
a
primary
mode
of
transmission.
Traditional
experimental
methods
studying
cough
dynamics
often
fall
short
in
replicating
complexity
coughs,
limiting
our
understanding
virus
This
study
introduces
novel
and
versatile
simulator
capable
wide
range
jet
profiles
with
high
accuracy
repeatability.
device
employs
synthetic
actuator
driven
by
signals
derived
from
parameters,
paired
an
aerosol
chamber
interchangeable
mouthpieces.
was
characterized
using
particle
image
velocimetry
flow
visualization
techniques,
demonstrating
its
ability
to
generate
jets
peak
velocities
ranging
approximately
3–39
m/s
velocity
times
8.75
60.00
ms.
simulated
exhibit
characteristic
starting-jet
interrupted-jet
stages
observed
coughs.
Calibration
maps
were
developed
allow
precise
tuning
enhancing
device's
versatility.
simulator's
reproducibility
validated
through
repeated
trials,
showing
consistent
characteristics
despite
turbulent
nature
jets.
pulsatile
provides
reliable
adaptable
platform
cough-generated
aerosols,
contributing
better
disease
transmission
development
effective
mitigation
strategies.
Язык: Английский