A Numerical Study of Worker Exposure to a Gaseous Contaminant: Variations on Body Shape and Scalar Transport Model

Abstract

Three-dimensional computational fluid dynamics simulations are used to investigate the distribution and level of contaminant concentrations in the true breathing zone (at the nose and mouth) when toxic airborne contaminants are released within an arm's length in front of the worker who has his back to the airflow. The effects of different body shapes on fluid flow and concentration patterns around the body in a wind tunnel were evaluated and clarified that a sharp body or a block may not be a good surrogate for the human form in consideration of occupational and environmental health studies. The comparison of the concentration field calculated with the Eulerian and Lagrangian methods revealed that the Eulerian method has a more diffusive nature than the Lagrangian method. The concentrations at different locations were also compared to determine the optimum sampling location. It was found that the concentration at the breathing zone may be significantly different from the one at the chest area. The influence of the heat flux from the body was studied at two different Reynolds numbers. Predictions indicate that the heat flux may have a significant impact on exposure especially when the convection induced by buoyancy dominates the flow.

Keywords:

• body shape
• numerical simulation
• scalar transport
• worker exposure

ACKNOWLEDGEMENTS

We particularly acknowledge Dr. Aaron J. Bird from NIOSH for his comments and help in providing the grid of the human torso. We'd like to express our appreciation to the editor whose valuable comments and suggestions make this paper much better than the original version.

This work was performed under a National Institute of Occupational Safety and Health project sponsored by the Centers for Disease Control and Prevention through grant R01 OH07587-01.

Notes

^A Some cells are hexahedral cells and the other are tetrahedral cells.