Transient CFD simulation of the respiration process and inter-person exposure assessment

Abstract

It is known that the person-to-person spreading of certain infectious diseases is related with the transmission of human exhaled air in the indoor environments, and this is suspected to be the case with the severe acute respiratory syndrome (SARS) outbreak. This paper presents the numerical analysis of the human respiration process and the transport of exhaled air by breathing, sneezing, and coughing and their potential impact on the adjacent person in a modeled room with displacement ventilation. In order to account for the influence of the thermal plume around the human body, a three-dimensional computational thermal manikin (CTM) with an accurate description of body geometry was applied. Some of the results were compared with those from former simulations and experiments. It was found that personal exposure to the exhaled air from the normal respiration process of other persons is very low in a modeled room with displacement ventilation. Personal exposure to pollution caused by sneezing or coughing is highly directional. When two occupants face each other the cross-infection may happen due to the long transport distance of the exhalation. r

Experimental and Numerical Investigation of Interpersonal Exposure of Sneezing in a Full-Scale Chamber

“…However, most of these studies were limited to numerical analyses. Gao and Niu (2006) carried out a numerical study in a room with two persons sitting opposite to each other. They found that cross infection may occur because of the long distances traveled by the sneezed air in a specific direction.…”

Characterization of non-isothermal flows typical of built environments in a laboratory scale model. Part II – Numerical predictions with CFD

“…[6e18]) by replacing it by the high-Reynolds number eddy viscosity formulation of the standard keε turbulence model (see Table 1). However, as known and highlighted by several authors, the airflow in some regions of a climatized room is not fully turbulent [19,20] and, therefore, using this high-Reynolds number equation for the effective viscosity may overestimate the turbulent diffusion.…”

“…These results are supported by those of Craven and Settles [18] who modelled the thermal plume from a highly simplified human model with the RNG keε model concluding that the predictions agree quite well with the 2D PIV measured data. Gao and Niu [19] used the RNG keε model, with a differential equation to obtain the effective viscosity at low-Reynolds number when simulating the airflow around a seated human body in a displacement ventilated room, confirming that such model has the potential to adequately predict the spread mechanisms of exhaled pollutants. However, the authors did not assess or validate with experiments the model predictions.…”

“…This may be crucial for the numerical results accuracy as the airflow in some regions of climatized rooms is not fully turbulent [19,20] and, therefore, using the high-Reynolds number approach for the effective viscosity may overestimate the turbulent diffusion. This issue is addressed herein through the evaluation of the improvement of such differential equation for the effective viscosity in predicting built environment flows.…”

Experimental Investigation of Exhaled Aerosol Transport Under Two Ventilation Systems

“…Other researchers have numerically studied the transport of bacteria through an expiratory process in an isolation room (Zhao et al 2009;Richmond-Bryant 2009;Huang and Tsao 2005). The detailed features of body geometry have also been examined in a study of personal exposure when two occupants are positioned opposite each other (Gao and Niu 2006). In comparison with the outcomes of numerical modeling, the experimental results obtained in this latter study were limited and far from complete.…”