On the inconsistencies related to prediction of flow into an enclosing hood obstructed by a worker.
J Occup Environ Hyg 2010 Jun; 7(6):315-325
The recirculating flow structures formed in the wake of a worker standing in front of an enclosing fume hood were numerically investigated. Two- and three-dimensional, unsteady, laminar/turbulent computations were performed for a Reynolds number (Re) range of 1.0x10 3 - 1.0 x10 5. The standard k - e, Renormalization group (RNG) k - e, and Shear Stress Transport (SST) k - w models were used in Unsteady Reynolds Averaged Navier-Stokes (URANS) computations, and the results were compared with each other and also with the previous predictions reported in the literature. Numerical issues regarding the grid convergence and the inadequacies of turbulence models that may come into play at low Reynolds numbers were addressed. On the whole, SST k - w model was found to be promising for qualitatively accurate prediction of both steady and unsteady recirculatory flow patterns in the wake of the worker. On the other hand, the standard and RNG k - e models failed in prediction of anticipated unsteadiness at low Reynolds numbers. In a more realistic three-dimensional simulation with SST k - w model, the anticipated unsteady and recirculating flow field in the wake of the worker was captured. Present results seem to qualitatively agree with the deductions made from experimental analyses in the literature while conflicting with some aspects of the previously reported numerical results. The apparent inconsistencies observed between the current results and those published in the literature were elucidated.
Fumes; Air-flow; Air-quality-control; Airborne-particles; Laboratory-workers; Laboratory-techniques; Exposure-assessment; Exposure-methods;
Author Keywords: enclosing fume hoods; turbulent flows; wake flows
Ertan Karaismail, Mechanical and Aerospace Engineering Department, West Virginia University, Morgantown, WV 26506-6106
Journal of Occupational and Environmental Hygiene
West Virginia University