Dynamic characterization of wind pressure fluctuations in separated and reattaching flows

Abstract

Flow separation and reattachment over bluff bodies has been a primary concern in wind engineering community as it may generate large suction pressure. This study re-visits the characteristics of wind pressure underneath the separated shear layer, with emphasis on diagnosing the underlying dynamic properties. Nonlinear dynamic analysis techniques, namely recurrence plot and recurrence quantification analysis are applied to reveal and compare the wind pressure dynamics associated with different test conditions. The results indicate that the dynamic behaviour of wind pressure is closely tied with leading edge shape, turbulence intensity, as well as turbulence scale. Generally, the underlying dynamics of wind pressure become less deterministic as the measurement position moves from leading edge towards downstream. Such pattern is reversed once the descriptive indicator reaches its minimum. The position of such minimum value corresponds well to the downstream boundary of the reverse flow region. Moreover, the minimum value of dynamic descriptive indicator, as well as the reverse position in its distribution pattern, is correlated with the leading edge shape. On the other hand, the minimum value of dynamic descriptive indicator is also dependent on turbulence scale, while the reverse position in the distribution pattern of dynamic descriptive factor is dependent on turbulence intensity.