Investigation into Effects of Turbulence Integral Length on Wind Loads Acting on Tall Buildings Using Large Eddy Simulation

To investigate the influence of turbulence integral length on the wind pressure value and distribution on the surface of tall buildings and determine the reasonable value of turbulence integral lengths, a large eddy simulation (LES) was conducted under different turbulence integral lengths to represent the wind flow field around the commonwealth advisory aeronautical research council(CAARC)standard tall building model in exposure category B. The obtained results were compared with those from the wind tunnel test. It is found that the LES is a feasible tool to represent the wind flow around a high building and the distribution of wind pressure on the building surface. It is also found that with the increase in the turbulence integral length, the energy of turbulent fluctuation increases, resulting from the deformation of flow average movement; the mean wind speed will decrease, and hence, the turbulence intensity will increase. It is also found that the fluctuation of wind pressure decreases by 15% on the side face, while the reattachment point of separated flow moves forward. Meanwhile, the local peak at the high-frequency range as well as the peak of aerodynamic base moment and torque spectrum decrease. While the Strouhal number of the layer is essentially the same at a height lower than 0.4 times the height of the building, it decreases by 20%-30% with the increase in height, and the drag coefficients of the mean layer decrease by 5%-10%. The results also show that the mean coefficients of the wind pressure in the windward side reduce by 2%-5%, with a decrease of 12%-17% in the crosswind side and leeward side. The investigation further finds that the turbulence integral length has minor effects on correlations of horizontal wind pressure in the windward side and crosswind side in the upwind direction, and the lift on the layer and drag on the layer at a height less than 0.8 times the height of the building. With the increase in the turbulence integral length, the correlation coefficient of the horizontal wind pressure increases respectively by 5%-10%and 15%-25% in the leeward and crosswind sides in the downwind direction, and the correlation coefficient of the drag of the layer increases by 25%-50% at a height above 0.8 times the height of the building. When the adjustment coefficient of the turbulence integral length in exposure category B is 0.4, the results of wind load obtained by LES are more consistent with the test results.