| Effect of turbulence on the pressure distributions on two surface mounted square prism models, one with dimensions twice the other, are investigated. Mean and fluctuating pressure distributions on the front, side, wake and roof faces of the three-dimensional bluff bodies exposed to a simulated neutral urban boundary layer flow in the wind tunnel are presented. All the measurements were carried out for 0 degree approach wind except for the roof face. For the roof face, measurements were conducted for both 0 and 45 degree wind. Simultaneous pressure measurements at typical locations on the same face of the model as well as on different faces were carried out to obtain pressure correlations.; The pressure distributions on the side and roof faces of both models showed reattachment of the flow. The trends of the pressure distributions including the peak pressure distributions were the same for both models. The pressure coefficients for the smaller model was lower than for the taller one due to the different ratios of the heights of model and boundary layer.; Side face cross correlation measurements showed clearly side flow reattachment. Smoke flow and sand erosion visualization study also corroborated very well the flow reattachment. From the analysis of pressure spectra, no vortex shedding was observed on the side face. Changing the Reynolds number did not change the small scale content of the turbulence.; The characteristics of the boundary layer measured in the wind tunnel were compared with atmospheric data and a model scale of around 1:400 was obtained.; A simple cost effective common sample and hold computer controlled data acquisition set-up for simultaneous pressure and velocity measurements was devised. A simple and accurate dynamic calibration technique was developed to determine the optimum upper limit of flat frequency response of pressure transducer-tube systems. |
