Sensitivity analysis of wind pressure coefficients on CAARC standard tall buildings in CFD simulations

Constructing tall buildings has been a common trend for many cities due to rapid increase of population, therefore, it is essential to analyze wind pressure around and over these tall buildings. CFD simulation is an effective approach to realize this, in which CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building has been a well-acknowledged model to validate and calibrate tall building models. Nevertheless, less work has been conducted to study sensitivity of wind pressures over CAARC standard tall building to geometric and computational parameters in CFD simulation. This paper is therefore designed to fill this gap by analysing impacts of various parameters like turbulence model, approaching-flow speed and grid type on wind pressure coefficients over CAARC buildings. In this paper, wind pressure coefficients over CAARC models subjected to four wind directions were numerically analyzed for validating the correctness and effectiveness of numerical model. Sensitivity of wind pressures to geometric and computational parameters was analyzed through comparisons of deviation and absolute deviation. Results indicated that various phenomena such as fluid separation, vortex, wake effect and reattachment were sensitive to wind direction, resulting in great variations in wind pressure. Maximum positive wind pressure coefficients emerged around 0.8-0.85 H of windward surface, while maximum negative one occurred at foreside of top surface. Furthermore, turbulence model had significant influences on the accuracy of numerical results, where Realizable k-ε and SST were the most accurate turbulence models, and standard k-ε and RNG k-ε models were the second accurate ones, but BSL was not recommended for wind resistance design. Approaching-flow speed and grid type exerted insignificant influences on pressure coefficient distribution, while grid resolution had significant effects on negative wind pressure distribution. In general, conclusions obtained in this study can assist structural engineers to select practical geometric and computational parameters in predicting wind pressure distribution against tall buildings.