Flow visualisation studies of aerodynamic characteristics of an open-top chamber.
Studies to determine potential locations of ingress of ambient air into an open-top chamber, using flow visualisation, are described. Rates of chamber ventilation necessary to avoid ambient air entrainment have been estimated from wind tunnel experiments. The dependence of the exit velocity of air from the chamber on the ambient air velocity was non-linear, so that for low wind speeds other mechanisms are more important than for high ambient air flows. Wind speeds ranged from 0.5m s(-1)<Uo<12m s(-1) outgoing atmospheric boundary layer had little effect on the probability of entrainment.