Unsteady flow on the sides of a 6 m cube

Four ultrasonic anemometers have been used to measure flow velocities at two groups of positions at mid-height on a 6 m cube. One other ultrasonic anemometer, located upstream at cube height, provided reference wind data. The results obtained provide a picture of the mean and fluctuating parts of the flow. Mean velocity results indicate that with the wind perpendicular to one face, the flow detaches at the windward edge but is reattached to the sides by about x/h=0.83. However, probability analysis shows that the velocity at this point is reversed for 54% of the time. In addition it is shown that while some of the fluctuations can be attributed to a quasi-steady response to variations in wind direction, the influence of building-induced turbulence is also very apparent. These results illustrate the highly turbulent and unsteady nature of flow on the sides of the cube.