Search arXiv⌕ Search

arXiv · 2004.09354

The Flow Physics of COVID-19

Abstract

Flow physics plays a key role in nearly every facet of the COVID-19 pandemic. This includes the generation and aerosolization of virus-laden respiratory droplets from a host, its airborne dispersion and deposition on surfaces, as well as the subsequent inhalation of these bioaerosols by unsuspecting recipients. Fluid dynamics is also key to preventative measures such as the use of face masks, hand-washing, ventilation of indoor environments, and even social distancing. This article summarizes what we know, and more importantly, what we need to learn about the science underlying these issues so that we are better prepared to tackle the next outbreak of COVID-19 or a similar disease.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Rajat Mittal, Rui Ni, Jung-Hee Seo. 2020-04-22. The Flow Physics of COVID-19. https://doi.org/10.1017/jfm.2020.330

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Kinematic Closure of Drop Impact

Predicting how far a liquid droplet spreads upon impacting a solid surface is governed by a complex competition between inertia, surface tension, and viscous dissipation. Existing models typically estimate this maximum spreading diameter by prescribing the spreading time or velocity from a decoupled asymptotic limit, restricting predictive accuracy across regimes. Here, we formulate a reduced kinematic description by resolving both the characteristic spreading time and spreading velocity from an energy balance coupling capillary storage and viscous dissipation. Unifying these two asymptotically constrained closures via the kinematic relation $D_{\max} = V_s t_s$ yields a compact, parameter-free approximation for the maximum spreading ratio that bridges the inertio-capillary and inertio-viscous regimes. We quantify the accuracy of this reduced closure against the exact implicit energy relation and demonstrate that it quantitatively collapses our experimental measurements alongside extensive literature data across wide ranges of Weber and Ohnesorge numbers, droplet sizes, and surface wettabilities without adjustable prefactors.

physics.flu-dyn↗

Azimuthal Instability in Oscillating Liquid Jets by the Weber Number Variations

This paper investigates the dependence of azimuthal mode growth rate of oscillating liquid laminar jets on the Weber number. The oscillating liquid laminar jets were simulated over a range of Weber numbers. The simulation setup was validated by comparing the instantaneous interface shapes and the visible azimuthal mode from experimental measurements. As the Weber number increases, the spreading angle rises due to the small surface tension, and higher azimuthal modes are observed. Fourier Transform analysis is used to find the exact azimuthal mode of the simulation results. The dominant azimuthal mode increases as the Weber number increases. A power-law dependence of the growth rate on the Weber number is identified, with the obtained exponents showing good agreement with linear instability analysis. Furthermore, the rescaled Fast Fourier Transform (FFT) results collapse onto a single growth curve for each azimuthal mode, validating the proposed power-law for predicting the growth rates of oscillating liquid jets.

physics.flu-dyn↗

Streamwise dispersion with interphase mass transfer through a tube

Reactive solute transport in shear flows is of broad importance in chemical engineering, liquid--solid chromatography, and environmental mechanics, particularly in flow reactors and fluidic devices involving interphase mass transfer. Based on the recently developed streamwise dispersion theory for inert solutions (Guan & Chen, 2024, J. Fluid Mech., vol. 980, A33), we present an analytical model for reactive dispersion of chemically active solutes characterized by first-order, irreversible surface reactions. The extension is not a simple perturbation because the reactive boundary destroys mass conservation with streamwise and radial derivatives coupled. The model establishes how the microscopic kinetic reactivity and radial eigenmodes combine to determine a newly defined (effective) local exchange rate. We derive rigorous explicit solutions for the local moments, concentration, and phenomenological transport coefficients at arbitrary reactivity, in quantitative agreement with numerical simulations across all regimes. For tube Poiseuille flows, we reveal pre-asymptotic behaviours including sign-changing radial exchange, reactivity-enhanced drift, reactivity-reduced dispersivity, and non-Gaussian concentration profiles. Small- and large-Damköhler-number asymptotics for the local and global transport coefficients identify the reaction-limited and diffusion-limited regimes, connecting the conservative case to the Dirichlet limit at infinite reactivity. This streamwise perspective could advance our understanding of macroscale transport in chemically active systems.

physics.flu-dyn↗