Air movement around a worker in a low-speed flow field

A knowledge of the air movement around a worker in a low-speed airflow is important in a number of areas: containment testing of fume cupboards; testing of personal dust samplers; testing of LEV effectiveness; and measurement of worker exposure. Measurements of velocity vectors around the upper torsos of manikins and a human in low-speed airflows have been made using a laser Doppler anemometer. Both heated and unheated manikins, as well as a 'breathing' manikin were used. The results show that quite distinctive flow patterns develop with heated and unheated bodies. Comparison of the flows around two- and three-dimensional manikins with that around a human shows that only a three-dimensional heated manikin gives good results. The unheated breathing manikin gave results which were unrepresentative of the real situation. A suitable manikin for use in sampling or testing in low-speed airflows would have a heated, rounded, three-dimensional body of reasonably human dimensions and would be non-breathing and clothed.