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Assessment of concentration and velocity field using coarse grid.

Tamanna-S; Ahmed-M; Lee-E; Feigley-C; Khan-J
American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 2004 May; :50
Assessment of expsure in industrial hygiene is an important concern. In order to perform contaminant exposure assessment in a workroom, it is necessary to predict the steady state concentration distribution in a room as a function of room-air exchange rates and ventilation air inlet and outlet locations. Existing model equations do not always predict the spatial concentration variations to the desired accuracy. As a result, in an alternate approach, the analysis of flow field and assessment of concentration in the room is determined by computational fluid dynamics simulations with fine grid. This approach can be computationally expensive and very time-consuming, particularly for threedimensional cases. Researchers in the past have studied multi-zonal method and even coarse grid (for 2-D cases) CFD simulations to minimize the computational cost at the same time keeping the accuracy of predicted results within reasonable error limits. In this paper, a similar approach has been taken where 3-D CFD simulations are perfonned for various ventilation flow rates and relative contaminant source, inlet, and outlet locations of the ventilation air. In order to reduce the time requirement for CFD analysis, coarse grid simulations have been studied for three cases: two-dimensional, semi-two dimensional, and three-dimensional, and these data have been compared with the fine grid CFD simulations. The analyses show that two-dimensional and semi-two dimensional cases can have good agreement with fme grid solutions for both velocity profile and concentration estimates. In three-dimensional cases, the coarse grid simulation method provides reasonable results only in rooms that are geometrically symmetric. For most other rooms, CFD results do not show satisfactory agreement in assessing concentrations, whereas velocity profiles show better agreement than concentration in three-dimensional cases. This paper presents several CFD results with varying grid sizes and some experimental results to demonstrate the validity of the conclusions obtained.
Air-flow; Air-contamination; Air-quality; Emission-sources; Temperature-effects; Sampling; Air-sampling; Exposure-levels; Industrial-hygiene; Models
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American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia
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University of South Carolina at Columbia, Columbia, South Carolina