Study Of Influence Of Chamfer And Corner Recession Modifications Of Square Cylinder On Wind Load Based On Large Eddy Simulation

The square cylinder has been widely used in many engineering applications such as buildings,bridges,and other structures.Because of simple cross-section and fixed separation point,square cylinder has been one of the main research objects in computational fluid dynamics(CFD).The aerodynamic optimization is an effective method to reduce the wind load and wind-induced vibration response for such types of structures by controlling flow separation and changing the surrounding wind environment.Chamfer and corner recession modification are two common modifications of square cylinders used to reduce the aerodynamic forces.This paper investigates the influence of chamfer and corner recession modifications on wind loads for high-rise buildings with a square cylinder based on large eddy simulation(LES)method.The main research aspects covered in this study are as follows:(1)Investigates the influence of the Chamfer and corner recession modifications on wind loads for a quasi-three-dimensional square cylinder based on large-eddy simulation method in a uniform flow field.The distribution of wind pressure coefficients and the aerodynamic coefficient were analyzed.The simulated results were verified by comparison with the experiments and previous numerical simulation results and it has shown good agreement.Numerical simulation of unsteady flow around three-dimensional square cylinder with corner modifications is conducted to study the influence of aerodynamic shapes(chamfer and corner recession)and wind angles on wind loads,the aerodynamic forces,flow field,and the vortex patterns around the cylinder are discussed in detail to study the flow mechanism.Results show that the chamfer and corner recession modifications can significantly reduce the wind pressure on the surface of the square cylinder.Its found that with the change of wind angles,the distribution of high and low-pressure areas on the surface of the square cylinder also changed.It's also found that the corner modification and wind angles change can significantly change the numbers,location,and size of the separated vortex around the square cylinder.(2)Study on the synthetic method of inflow pulsation in the turbulent boundary layer wind filed by LES.Based on the self-maintaining boundary conditions of the atmospheric boundary layer,parameters adjust,and improvement of the Fluent built-in vortex synthesis method was carried out.Three-dimensional square cylinder in the turbulent boundary layer wind field is studied.The sufficient,applicability,and accuracy of the inflow pulsation synthesis method was proved.In this paper,the wind pressure coefficient and wind field parameters such as average wind profile,turbulence profile,and fluctuating wind speed spectrum were compared with wind tunnel tests.Results show that the vortex synthesis method can accurately and conveniently reproduce the characteristics of the turbulent boundary layer wind field and accurately predict the average and fluctuating wind pressure coefficient distribution on the surface of the structure,It is an effective method for large-eddy simulation to synthesize the inflow pulsation.(3)The effect of chamfer and corner recession modification with different wind angles on wind loads by adopting the turbulent boundary layer of a square cylinder and using the parameters which verified in this paper is carried out by LES.The influence of aerodynamic shape and wind angles on the wind loads of the structure in terms of the aspects of wind pressure coefficients on different surfaces and at different hight,and combine with the analysis of time-averaged and transient flow around cylinder were analyzed.Results show that chamfer and corner recession modifications and wind angles change can significantly influence the size and distribution area of the wind pressure on the surface of the square cylinder,and change the form of the separated vortex on the side of the square cylinder.Its found that the distance change between the vortex core and the wall of the symmetric vortex on the leeward side and the distance between the vortex core and the wall,lead to reduce the wind load,especially on the sides and leeward of the structure.