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Discrete Vortex Methods for the Simulation of Boundary Layer Separation Effects on Worker Exposure.

PB91185249

Publication Date	1991
Personal Author	Flynn, M. R.; Miller, C. T.
Page Count	29
Abstract	A computer model was developed to solve the governing equations of fluid mechanics for the time dependent air flow around a worker immersed in a uniform free stream. A main feature of the model was the ability to capture the formation and evolution of the near wake, reverse flow zone; this made it possible to examine the influence of changing air direction, worker position, and air speed on the position and size of the near wake zone. The direction of air flow with respect to the worker and the contaminant source was an important factor in determining the concentration of pollutant in the breathing zone. The phenomenon of boundary layer separation was responsible for the formation of rotating eddies on the downstream side of the worker. The discrete vortex method was found to effectively simulate the time dependent flow phenomenon of vortex shedding past an elliptic cylinder. The simulation was a valuable tool in understanding how the recirculation zone forms and changes periodically in time. The model required substantial computer resources to examine the vortex shedding phenomenon.
Keywords	Air sampling Boundary layer flow Computerized simulation Personnel Occupational exposure Industrial hygiene Air flow Vortices
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	68A - Air Pollution & Control 68G - Environmental Health & Safety 94D - Job Environment 41I - Job Environment
Corporate Authors	North Carolina Univ. at Chapel Hill. Dept. of Environmental Sciences and Engineering.
Document Type	Technical Report
NTIS Issue Number	199116

Discrete Vortex Methods for the Simulation of Boundary Layer Separation Effects on Worker Exposure.

Discrete Vortex Methods for the Simulation of Boundary Layer Separation Effects on Worker Exposure.
PB91185249

Publication Date	1991
Personal Author	Flynn, M. R.; Miller, C. T.
Page Count	29
Abstract	A computer model was developed to solve the governing equations of fluid mechanics for the time dependent air flow around a worker immersed in a uniform free stream. A main feature of the model was the ability to capture the formation and evolution of the near wake, reverse flow zone; this made it possible to examine the influence of changing air direction, worker position, and air speed on the position and size of the near wake zone. The direction of air flow with respect to the worker and the contaminant source was an important factor in determining the concentration of pollutant in the breathing zone. The phenomenon of boundary layer separation was responsible for the formation of rotating eddies on the downstream side of the worker. The discrete vortex method was found to effectively simulate the time dependent flow phenomenon of vortex shedding past an elliptic cylinder. The simulation was a valuable tool in understanding how the recirculation zone forms and changes periodically in time. The model required substantial computer resources to examine the vortex shedding phenomenon.
Keywords	Air sampling Boundary layer flow Computerized simulation Personnel Occupational exposure Industrial hygiene Air flow Vortices
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	68A - Air Pollution & Control 68G - Environmental Health & Safety 94D - Job Environment 41I - Job Environment
Corporate Authors	North Carolina Univ. at Chapel Hill. Dept. of Environmental Sciences and Engineering.
Document Type	Technical Report
NTIS Issue Number	199116