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Airflow pattern around a worker in a uniform freestream.
Am Ind Hyg Assoc J 1991 Jul; 52(7):287-296
Airflow patterns around a worker in a uniform free stream were analyzed to assess the effect of boundary layer separation on the concentration of toxic airborne contaminants in the breathing zone of a worker. Three dimensional airflow patterns were measured around a mannikin placed in a wind tunnel using a smoke visualization technique and hot wire anemometry. The data were analyzed according to a mass balance equation which predicted that the concentration of a contaminant in a worker's breathing zone was related to the rate of vortex formation and vortex shedding on the downstream side of the body. Airflow at chest height was characterized primarily as downwash. In the region between the chest and elbow both downwash and vortex shedding occurred. Vortex shedding predominated between the waist and hips. In the regions where vortex shedding occurred, each vortex was shed downstream at a frequency having an average Strouhal number of 0.19. The average area of each vortex was equal to 0.7 times that of a circle having a diameter equal to the width of the mannikin. The authors conclude that airflow around a person immersed in a uniform free stream has a three dimensional motion characterized by a significant amount of vortex shedding on the downstream side.
NIOSH-Publication; NIOSH-Grant; Control-technology; Air-flow; Work-environment; Mathematical-models; Industrial-hygiene; Laboratory-testing; Simulation-methods
Environmental Sciences & Engr University of North Carolina Rosenau Hall 201H Chapel Hill, NC 27514
Issue of Publication
American Industrial Hygiene Association Journal
University of North Carolina Chapel Hill, Chapel Hill, North Carolina
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division