Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface tension effects on flow dynamics and alveolar mechanics in the
  acinar region of human lung   Computational fluid dynamics (CFD) simulations, in-vitro setups, and
experimental ex-vivo approaches have been applied to numerous alveolar
geometries over the past years. They aimed to study and examine airflow
patterns, particle transport, and particle-alveolar wall deposition fractions.
These studies are imperative to both pharmaceutical and toxicological studies,
especially nowadays with the escalation of the menacing COVID-19 virus.
However, most of these studies ignored the surfactant layer that covers the
alveoli and the effect of the air-surfactant surface tension on flow dynamics
and air-alveolar surface mechanics. The present study employs a realistic human
breathing profile of 4.75 to emphasize the importance of the surfactant layer
by numerically comparing airflow phenomena between a surfactant-enriched and
surfactant-deficient model. The acinar model exhibits physiologically accurate
alveolar and duct dimensions extending from lung generations 18 to 23. Proximal
lung generations experience dominant recirculating flow while farther
generations in the distal alveolar region exhibit dominant radial flows. In the
surfactant-enriched model, surface tension values alternate during inhalation
and exhalation. In the surfactant-deficient model, only water coats the
alveolar walls. Results showed that surfactant deficiency in the alveoli
adversely alters airflow behavior and generates unsteady chaotic breathing
through the production of vorticities, accompanied by higher vorticity and
velocity magnitudes. In addition, high air-water surface tension in the
surfactant-deficient case was found to induce higher shear stress values on the
alveolar walls than that of the surfactant-enriched case. Overall, it was
concluded that the presence of the surfactant improves respiratory mechanics
and allows for smooth breathing and normal respiration.

12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
16
The categories of this paper are: stat