Characteristics of large pressures in regions of flow separation

Abstract

Large fluctuating suction pressures are generated in flow separation regions close to the leading edges on the roof of low rise buildings. The flow mechanisms that generate these pressures are the 2D separation bubble for flow perpendicular to the edge discontinuity and the 3D conical vortex for flow at oblique angles to the edge discontinuity. These pressure fluctuations depart from the Gaussian distribution with significantly greater probabilities at the negative tail of the probability distribution. The largest suction pressures are generated close to the leading corner for a wind orientation of ∼ 30°. Conditionally sampled data indicated that progressively larger section pressures in the separation regions were progressively spatially better correlated. Also, time averaged pressures and peak suction pressures were spatially better correlated under the 3D conical vortex than under the 2D separation bubble.