5 research outputs found
Airflows inside passenger cars and implications for airborne disease transmission
Transmission of highly infectious respiratory diseases, including SARS-CoV-2
are facilitated by the transport of tiny droplets and aerosols (harboring
viruses, bacteria, etc.) that are breathed out by individuals and can remain
suspended in air for extended periods of time in confined environments. A
passenger car cabin represents one such situation in which there exists an
elevated risk of pathogen transmission. Here we present results from numerical
simulations of the potential routes of airborne transmission within a model car
geometry, for a variety of ventilation configurations representing different
combinations of open and closed windows. We estimate relative concentrations
and residence times of a non-interacting, passive scalar -- a proxy for
infectious pathogenic particles -- that are advected and diffused by the
turbulent airflows inside the cabin. Our findings reveal that creating an
airflow pattern that travels across the cabin, entering and existing farthest
from the occupants can potentially reduce the transmission.Comment: 8 pages, 6 figures + supplementa
Recommended from our members
Fluid-structure interactions of energy-harvesting membrane hydrofoils
We study the kinematics, dynamics and flow fields generated by an oscillating, compliant membrane hydrofoil extracting energy from a uniform water stream at a chord-based Reynolds number ≈3×104. Hydrodynamic forces during the foil\u27s motion cause the membrane to dynamically morph its shape, effectively increasing the camber during the oscillation cycle. The membrane\u27s deflection is modelled using the Young–Laplace equation, with pressure term approximated from thin-airfoil theory. Simultaneous tracking of the membrane deformation and the surrounding flow field using laser profiling and particle image velocimetry, respectively, reveals the role of dynamic cambering in stabilizing the leading-edge vortices on the membrane. In this regime of operation, we obtain up to 160 % higher power extraction when compared to a rigid, symmetric hydrofoil. The present work provides a demonstration of how passive compliance of soft materials interacting with fluids may be exploited in tidal and fluvial energy extraction
Shape-Morphing Dynamics of Soft Compliant Membranes for Drag and Turbulence Modulation
We study the kinematics and dynamics of a highly compliant membrane disk
placed head-on in a uniform flow. With increasing flow velocity, the membrane
deforms nonlinearly into increasingly parachute-like shapes. These
aerodynamically elongated materials exhibit a modified drag law, which is
linked to the elastohydrodynamic interactions. We predict the unsteady
structural response of the membranes using a nonlinear, aeroelastic model -- in
excellent agreement with experimental measurements of deformations and force
fluctuations. With simultaneous membrane interface tracking, force measurements
and flow tracing, we reveal that a peculiar skewness in the membrane's
oscillations triggers turbulence production in the wake, thereby modulating the
drag. The present work provides a demonstration of the complex interplay
between soft materials and fluid turbulence, leading to new, emergent system
properties.Comment: 5 pages, 4 figures, Phys. Rev. Lett. (in press