Unsteady features of bluff body wake with application to building wake length

This study is targeted at obtaining fluctuating characteristics of building wakes through measurement of unsteady velocity fields with time-resolved particle image velocimetry (PIV). Proper orthogonal decomposition is applied to the PIV data to identify low-dimensional substructures of the building wake. This leads to a more reliable estimation of the fluctuating ground-level length of the building wake from an instantaneous PIV snapshot. The statistics of unsteady wake lengths is important in the probability-based risk assessment of critical events of wind environment around buildings such as dispersion of hazardous pollutants, pedestrian danger and risks to aircraft landings on airport runways.