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.