Interactions of exhaled buoyant jet flow and human motion-induced airflow: An experiment study in a water tank

Liu, Fan, Zhang, Lei, Luo, Zhiwen ORCID: https://orcid.org/0000-0002-2082-3958, Zhang, Chongyang and Qian, Hua 2023. Interactions of exhaled buoyant jet flow and human motion-induced airflow: An experiment study in a water tank. Building and Environment 242 , 110603. 10.1016/j.buildenv.2023.110603 Item availability restricted.

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Abstract

Indoor environments with displacement ventilation or under-floor air distribution commonly exhibit thermal stratification, which can impact the dispersion of droplets in exhaled air by moving human sources. This paper presented an experimental study using a water tank to simulate the coupling characteristics of exhaled airflow and human motion-induced oncoming airflow, especially in a stratified environment. The effects of exhalation velocity and movement speed were studied. Results show that the buoyant jet flow couples with the oncoming flow, firstly spreading forwards and upwards, forming the impinging region, where the penetration distance is found to vary linearly with the ratio of movement velocity and exhalation velocity. Then the coupled flow spreads backwards, forming the wake region behind the source, where the flow rises upwards, albeit at a slower rate than in motionless conditions. In the wake region, there is an obvious stagnant layer, which is exacerbated by the thermal stratification of the ambient fluid and much lower than the lock-up height of motionless buoyant jet flow. It is expected to provide scientific basis for formulating prevention and control measures in public spaces.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Architecture
Publisher:	Elsevier
ISSN:	0360-1323
Date of First Compliant Deposit:	11 July 2023
Date of Acceptance:	10 July 2023
Last Modified:	11 Nov 2023 10:16
URI:	https://orca.cardiff.ac.uk/id/eprint/160944

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