Comparative Study of Aerodynamic Coefficients of Prismatic and Twisted Tall Buildings with various Cross Sections using CFD

Abstract

The design of tall buildings is predominantly governed by the wind loads and response of the building when it interacts with the atmospheric boundary layer (ABL) as the tall building is standing in the ABL and behaves as the cantilevered obstruction to the wind flow in ABL. Wind-induced responses are the function of outer geometry of the building. So, by modifying the outer geometry, the aerodynamics of the tall buildings can be controlled, and therefore, the focus of the recent researches is shifted from conventional prismatic geometry along the height toward the twisting buildings to enhance the aerodynamic performance and reduce the wind-induced forces on the tall buildings. In this study, a series of numerical simulations are performed to compare the aerodynamic loads on tall prismatic buildings having different sections: square, pentagonal and hexagonal with their twisted forms using the unsteady RNG k-ɛ turbulence model in CFD. The comparison is made on the basis of mean wind coefficients, pressure contours and velocity profiles at different height. A total of eighteen building models (three prismatic and fifteen twisted) were analyzed, and results show that the aerodynamic load on the twisted buildings is on the lower side as compared to the prismatic buildings.