UCL Discovery

Abstract

There has been considerable interest in the interaction between buoyancy and wind pressure gradients on the overall structure of natural ventilation flows. Indeed, it has been shown that when wind and buoyancy forces act in opposition, it is possible that for certain wind speeds, multiple steady states may emerge, with a stable wind dominated and a stable buoyancy dominated regime being possible for identical conditions; while at lower wind speeds, the buoyancy dominated flow develops and higher wind speeds, the wind dominated flow develops. Such multiple states arise owing to the particular location of the upper vent on the upwind side of the building and the lower vent on the downwind side of the building. Here we show that with a more realistic design, upper openings on both sides of the building, there is a smooth transition through the different flow regimes, from the wind dominated to the buoyancy dominated regime, with no region of multiple steady states developing.