Determination of aerodynamic derivative for one degree of freedom square cylinder using large eddy simulation

This study investigates the applicability of using Computational Fluid Dynamics (i.e., CFD) simulations to evaluate the aerodynamic derivatives (i.e., AD) and Wind Structure Interaction (i.e., WSI) response of free vibrating bluff bodies. The study majorly focuses on three-dimensional simulations of a rigid cylinder with a square cross-section that is elastically supported and constrained to move only in the transverse direction under wind loading. Primarily, to validate the method, the square cylinder was kept stationary, and the force coefficients were calculated at different wind angles of attack. Following that, to determine the AD, the free vibrations method or more precisely named the impulse response [1,2] was used, where the rigid square cylinder was first pushed a fixed distance and then left to freely vibrate. The model was assigned a definite mass and damping ratio, while supported on springs with discrete stiffness in the transverse direction. Finally, the amplitude of vibration was determined through a MATLAB code employing the Newmark Beta Method. This approach was widely applied in the literature for streamlined bodies and, up to the knowledge of the authors, was not validated for the sharp-edged bluff bodies. Eventually, it was concluded that the approach used is valid and could be used in the future to estimate the flutter derivatives as well as the amplitude of vibrations for square cross-section bodies. •The applicability of aerodynamic derivatives model for bluff bodies was investigated.•Large eddy simulation model was used to evaluate wind loads for square cylinder.•Computational results were verified with experimental wind tunnel tests.•The dynamic response was evaluated based on the aerodynamic derivatives.