In order to control the concentration of pollutants in the industrial workrooms and laboratories, local ventilation systems are widely used. Hood is the most important part of this system that has various types. Investigating the flow field around the hood and the induced velocity at a specified distance from the hood opening is of special importance in designing of hood. In this paper, the airflow around flanged hood’s opening with both circular and rectangular cross-sections has been modeled using computational fluid dynamics (CFD). Numerical modeling is accomplished assuming inviscid flow and the result is compared with that of potential correlations exist for circular and rectangular openings. The comparisons show good agreement. At the next step the flow field has been analyzed using , RNG turbulence model. Results of this case show that although there are differences in velocity vector magnitudes near the opening, generally there is a very small deviation from that of potential flow at centerline. But for points far from the centerline, deviation is significant because of the viscosity and boundary layer effects near the wall. Therefore, considering the real flow field and turbulence for modeling airflow around flanged hoods opening is inevitable.

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