Recent Developments and Future Directions in Flow Visualization: Experiments and Techniques
Fluids,
Год журнала:
2025,
Номер
10(2), С. 23 - 23
Опубликована: Янв. 22, 2025
Flow
visualization
has
long
been
a
critical
tool
for
understanding
complex
fluid
dynamics
in
both
natural
and
engineered
systems
[...]
Язык: Английский
Top and Side Leakage Effects on Thermoregulation and Moisture Retention with Facemask Wearing
Journal of Respiration,
Год журнала:
2025,
Номер
5(2), С. 5 - 5
Опубликована: Апрель 3, 2025
Background/Objectives:
Mask-wearing-induced
discomfort
often
leads
to
unconscious
loosening
of
the
mask
relieve
discomfort,
thereby
compromising
protective
efficacy.
This
study
investigated
how
leakage
flows
affect
mask-associated
thermoregulation
and
vapor
trapping
inform
better
designs.
An
integrated
ambience–mask–face–airway
model
with
various
mask-wearing
misfits
was
developed.
Methods:
The
transient
warming/cooling
effects,
thermal
buoyancy
force,
tissue
heat
generation,
phase
change,
fluid/heat/mass
transfer
through
a
porous
medium
were
considered
in
this
model,
which
validated
using
Schlieren
imaging,
camera,
velocity/temperature
measurements.
Leakages
from
top
side
analyzed
comparison
no-leak
scenario
under
cyclic
respiration
conditions.
Results:
A
significant
inverse
relationship
observed
between
facial
temperature/humidity.
equivalent
impact
forces
exhalation
flow
inertia
both
experimentally
numerically,
indicating
delicate
balance
natural
convection
forced
convection,
is
sensitive
critical
thermo-humidity
regulation.
For
given
gap,
fraction
not
constant
within
one
breathing
cycle
but
constantly
increased
during
exhalation.
Persistently
higher
temperatures
found
nose
region
throughout
sealed
mitigated
inhalation
when
gaps
present.
Vapor
condensation
occurred
all
cases.
Conclusions:
temporal
variation
profiles
location
highlighting
feasibility
leveraging
temperature
relative
humidity
test
fit
quantify
fraction.
Язык: Английский
Visualization and Quantification of Facemask Leakage Flows and Interpersonal Transmission with Varying Face Coverings
Опубликована: Июнь 7, 2024
Although
mask-wearing
is
now
widespread,
knowledge
of
how
to
quantify
or
improve
its
performance
remains
surprisingly
limited
and
largely
based
on
empirical
evidence.
The
objective
this
study
was
visualize
the
expiratory
airflows
from
facemasks
evaluate
aerosol
transmission
between
two
persons.
Different
visualization
methods
were
explored,
including
Schlieren
optical
system,
laser/LED-particle
imaging
thermal
camera,
vapor-SarGel
system.
leakage
flows
escaped
aerosols
quantified
using
a
hotwire
anemometer
particle
counter,
respectively.
results
show
that
reduces
exhaled
flow
velocity
2~4
m/s
(with
no
facemask)
around
0.1
m/s,
thus
decreasing
droplet
speeds.
Cloth,
surgical,
KN95
masks
showed
varying
at
nose
top,
sides,
chin.
rate
also
differed
inhalation
exhalation.
neck
gaiter
has
low
filtration
efficiency
high
fractions,
providing
protection
efficiency.
There
considerable
deposition
in
mouth-nose
area,
as
well
neck,
chin,
jaw,
which
heightened
risk
self-inoculation
through
spontaneous
face-touching.
A
face
shield
plus
surgical
mask
greatly
reduced
droplets
head,
face,
indicating
double
coverings
can
be
highly
effective
when
single
insufficient.
system
provided
practical
approach
interpersonal
under
close
contact
scenarios
with
different
coverings.
Язык: Английский