Study On Pressure Oscillation Of Unsteady State Numerical Wind Tunnel Simulation

With the development of science and technology.the improvement of the national economy,more lightweight and high-strength materials have been used in the construction industry.However,more super-tall buildings,large-span buildings and other novel and unique architectural shapes and structural forms have been emerged.The building is also more sensitive to wind,so wind loads are becoming more and more important for buildings from both the perspective of structural design safety and the comfort of living.At present,the load specification does not give accurate body shape coefficients for such oversized and complex buildings,and it is impossible to accurately determine the wind load on the building surface.At the same time,it cannot be reasonably determined that the wind load of the structure will not only cause damage to the structure and Damage,and even threaten the safety of people’s lives and property,so determining the reasonable wind load is the key to structural wind resistance design.In recent years,with the development of computers and the maturity of computational fluid dynamics,unsteady state numerical wind tunnel simulation as a direction of numerical wind tunnel simulation is about to become one of the main analytical methods of structural wind engineering.The wind load on the flow field and the building surface mainly includes the average pressure and the pulsating pressure.The reasonable determination of the pressure is very important.The pressure oscillation problem is the main factor affecting the pressure in the unsteady numerical wind tunnel simulation.The existence of pressure oscillation leads to various points in the calculation domain.The instability of the pressure is used to calculate the inaccuracies of the wind load,especially the wind pressure of the retaining member.Therefore,this paper studies the pressure oscillation problem.Based on the large eddy simulation method,the unsteady numerical wind tunnel simulation is carried out for the windless wind profile,the wind speed profile with wind speed profile and the building calculation domain with wind speed profile.Under the condition of different parameters,the influence of different parameters on the pressure oscillation provides a reference for improving the calculation accuracy of the unsteady numerical wind tunnel simulation.In this paper,large eddy simulation method,stochastic turbulence synthesis method,UDF and other measures are used to realize unsteady numerical wind tunnel simulation.Unsteady numerical wind tunnel simulation is performed on an empty wind field with uniform wind speed at the entrance.The varying turbulence intensity is studied and derived.The influence of parameters such as turbulence integration scale and grid size on pressure oscillations.The turbulence intensity,turbulent integral scale,and pulsating wind speed power spectrum of the mean wind speed profile and the pulsation characteristics of the wind are added to realize the numerical simulation of an unsteady state wind tunnel under the condition of a type B wind speed profile.The effect of grid size and calculation time step on pressure shock in air wind field.In addition,the pressure oscillations of the calculation domain with buildings under unidirectional and multi-directional wind speed conditions at the inlet B-type wind speed profile are studied.The effects of varying grid sizes and calculation time steps on the flow field and the pressure shocks on the building surface are analyzed,and on the building surface.Influence of pressure coefficient distribution.On this basis,in order to obtain an effective method to solve the pressure shock,an additional calculation domain method and a method of changing the grid size are proposed.The method is applied to the simulation of a non-steady-state numerical wind tunnel,and the simulation results are compared and analyzed.The results show that the two pressure shock solutions proposed in this paper can effectively alleviate the pressure shock problem and provide a certain reference value for structural designers to improve the pressure calculation accuracy of non-steady-state numerical wind tunnel simulation.