Transient transport model of particles resulting from high momentum respiratory activities: Inter-personal exposure

Abstract

a b s t r a c tIn this work, a transient mathematical multi-region zonal transport model of particle behavior resulting from high momentum respiratory activities (HMRA) is developed focusing on the transient interpersonal exposure (IPE) in indoor spaces ventilated by displacement ventilation (DV) systems. The developed model was validated by experimentation and by published empirical data.Three stages are identified with respect to time for the variation of the IPE: a first stage dominated by the propagation and decay of the exhaled jet, a particles' redistribution stage, and a particles' removal stage. The inhaled dose is affected by the DV flow rate, cough velocity, particle diameter and distance between the occupants. The DV system with a flow rate of 100 L/s reduced significantly the inhaled dose during particle redistribution and removal stages decreasing the total inhaled dose by 83% compared to a flow rate of 50 L/s. IPE is higher when particle diameter is increased from 1 to 20 mm due to the opposition of particle removal by the upward DV.A comparison between steady and transient modeling of the IPE showed that steady modeling captures the physics affecting particle spread due to HMRA but it over-predicts the inhaled dose. It is found that for a DV flow rate of 100 L/s and a cough velocity of 22 m/s during 1 s, and 1 mm particles, the minimum required distance between the occupants for a threshold inhaled dose of 10 À5 kg is nearly 0.5 m by transient modeling while it is 2.15 m by steady state modeling.

A novel circulated air curtain system to confine the transmission of exhaled contaminants: A numerical and experimental investigation

“…Coughing is simulated as steady model in this work, but steady simulation may not reflect the real exhalation airflow in transient respiratory activities. Habchi et al (2015) compared the steady and transient modeling of IPE and found that steady modeling over-predicted the inhaled dose of particle. Therefore, a transient model of pulse exhalation is carried out to simulate the exhaled airflow propagation of coughing process.…”

The function of aerosols in transmitting and infecting of respiratory infectious diseases and its risk prediction

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