Role of pulsatility on particle dispersion in expiratory flows

Abstract

Expiratory events, such as coughs, are often pulsatile in nature and result in vortical flow structures that transport respiratory particles. In this work, direct numerical simulation (DNS) of turbulent pulsatile jets, coupled with Lagrangian particle tracking of micron-sized droplets, is performed to investigate the role of secondary and tertiary expulsions on particle dispersion and penetration. Fully-developed turbulence obtained from DNS of a turbulent pipe flow is provided at the jet orifice. The volumetric flow rate at the orifice is modulated in time according to a damped sine wave; thereby allowing for control of the number of pulses, duration, and peak amplitude. The resulting vortex structures are analyzed for single-, two-, and three-pulse jets. The evolution of the particle cloud is then compared to existing single-pulse models. Particle dispersion and penetration of the entire cloud is found to be hindered by increased pulsatility. However, the penetration of particles emanating from a secondary or tertiary expulsion are enhanced due to acceleration downstream by vortex structures.

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Cited by in corpus (4)

• Dynamics of Evaporating Respiratory Droplets in the Vicinity of Vortex Dipoles
• Experimental and numerical investigation of inertial particles in underexpanded jets
• Neural stochastic differential equations for particle dispersion in large-eddy simulations of homogeneous isotropic turbulence
• On the Utility of a Well-Mixed Model for Predicting Disease Transmission on an Urban Bus