The Turbulent Schmidt Number for Transient Contaminant Dispersion in a Large Ventilated Room Using a Realizable k-ε Model.

Buildings with large open spaces in which chemicals are handled are often exposed to the risk of explosions. Computational fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large spaces. The turbulent Schmidt number (Sc_t) concept has typically been used in this regard, and most studies have adopted a default value. We studied the concentration distribution for sulfur hexafluoride (SF₆) assuming different emission rates and considering the effect of Sc_t. Then we examined the same problem for a light gas by assuming hydrogen gas (H₂) as the contaminant. When SF₆ was considered as the contaminant gas, a variation in the emission rate completely changed the concentration distribution. When the emission rate was low, the gravitational effect did not take place. For both low and high emission rates, an increase in Sc_t accelerated the transport rate of SF₆. In contrast, for H₂ as the contaminant gas, a larger Sc_t could induce a decrease in the H₂ transport rate. [ABSTRACT FROM AUTHOR]