Numerical simulation of airflow around a variable volume/constant face velocity fume cupboard.

Three-dimensional models of a variable volume/constant face velocity fume hood were developed and numerically solved to study the effect of the sash opening and rated face velocity on the flow patterns, especially in the exposure area of a person standing in front of the fume hood. These flow details are important in assessing the containment performance of the fume hood. For this study, fully turbulent flow was assumed to enter through the front hood window and exit through the exhaust duct. The finite-difference, control-volume technique, and standard k-epsilon models were employed and solved together with the equations for the conservation of mass and momentum using FLUENT/UNS version 4.2 to obtain the flow solutions. Unobstructed flow cases, as well as the simplified two-dimensional scenarios, also were investigated for comparison. Results indicated that there is no occurrence of recirculation leading to concentration buildup within the region between the person and fume hood entrance. Also, in conformance with other studies, the recirculating flow volume inside the hood decreased with increasing sash openings.