The effect of contaminant source location on worker exposure in the near-wake region.

The exposure of workers in the near-wake region due to a recirculating airflow was studied experimentally and numerically. A mannequin was installed in an open-ended tunnel and tracer gas was released at several locations downstream to determine the size and location of the reverse flow region. The contaminant transport into the breathing zone was found to depend strongly on the location of the release point. The airflow field was also determined numerically assuming a steady flow and using the standard k-epsilon turbulence model. After calculating the turbulent airflow field, a large number of submicrometre particles were released in different locations downstream of the mannequin to simulate the transport of gaseous contaminants. Although this method does not provide actual exposures, it does predict the tendencies in exposure variations due to different release points quite satisfactorily.