Vortex structures and wake flow analysis from moving manikin models

Abstract

Vortex shedding in the wake flow generated by moving bodies exerts considerable influence on pollutant dispersion. This study investigated the effects of different body shapes using scaled models 1/5th of realistic size, including thin and wide shapes, standing and walking poses. The airflow from moving bodies was simulated using computational fluid dynamics (CFD) with dynamic meshing to account for the manikin movement. Experimental data from a smoke visualisation technique provided validation data for computational simulations which included flow separation angle over the head computed through image processing. Vortex structures were visualised using an Omega vortex identification method and compared with experimental visualisations. The main objective of this study is to verify the CFD simulations with smoke visualisation in terms of predicting motion-induced vortex structures, thus helping identify contaminant transport around different shaped bodies during walking and when coming to a stop. The results showed matching locations and patterns of vortex structures between the smoke visualisation and CFD simulations. After the manikin came to a stop, the flow induced by the larger body was characterised by a longer residence time for airborne contaminants in the breathing region while a reduced flow residence time for the thinner bodied manikin.

Multi‐person movement‐induced airflow and the effects on virus‐laden expiratory droplet dispersion in indoor environments

“…We adopted numerical simulations in this study, and experimental data would validate the results. The renormalization group (RNG) k‐ε turbulence model performs well in predicting airflow patterns in indoor environments 12,31,32,38 . Hence, we took the RNG k‐ε turbulence model for calculation.…”

Human response to thermal environment and perceived air quality in an office with individually controlled convective and radiant cooling systems

“…Together with the effect of heat gains on air movement, the influence of occupants' movements should also be considered. Previous studies on this indicated that the human movement in the indoor environment has an influence on the dynamic airflow (DeHart, 2003;Mangili & Gendreau, 2005;Mazumdar et al, 2011;Tao et al, 2020). An upward air vortex and a strong downward airflow were detected behind the moving body at different moving speeds.…”

Effect of Walking Modes and Temperatures on the Robustness of Ventilation Systems in the Control of Walking-induced Disturbances

“…Many studies emphasized the importance of the flow field (Tao et al, 2017(Tao et al, , 2018Liu et al, 2020). The movement of people would cause serious disturbances to the surrounding airflow, which would affect the diffusion of particulate matter (Cao et al, 2017;Tao et al, 2021). Therefore, the high robustness value of the flow field could be reduced by the disturbances caused by human walking.…”