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A field investigation of the flow and diffusion around a model cube

1982; Elsevier BV; Volume: 16; Issue: 2 Linguagem: Inglês

10.1016/0004-6981(82)90435-8

1878-2442

Yasushi Ogawa, Susumu Oikawa,

Fluid Dynamics and Vibration Analysis

A field experiment was conducted to investigate the downdraft phenomenon behind a simple cube in flat terrain. The effects of wind direction on the mean wind velocity, turbulent intensity, power spectra, cavity wake length, and rooftop and wake region concentrations were measured by eight ultrasonic anemometers, a three-dimensional network of wind vanes, and SF6 tracer gas experiments. As the wind direction from the plane perpendicular to the upwind face of the model increased, the wake region shifted causing shifts in both the velocity deficit region and increased turbulent intensity region. Because of the flow/building interaction, the normalized u and v component peak frequencies behind the cube (at YH = 0) increased but began to recover to their upwind values as XH increased. As θ, the angle between the wind direction and the normal to the upwind face, increased, the power spectra for those observation points which moved into the wake region shifted to smaller λm. At θ = 0°, the cavity wake length, LcH, was approximately 1.7 and the velocity deficit region extended past XH = 6.5. As θ increased, the maximum normalized ground level concentration increased.